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2010 - 2011: Earth's most extreme weather since 1816?

Posted on 27 June 2011 by Jeff Masters

Every year extraordinary weather events rock the Earth. Records that have stood centuries are broken. Great floods, droughts, and storms affect millions of people, and truly exceptional weather events unprecedented in human history may occur. But the wild roller-coaster ride of incredible weather events during 2010, in my mind, makes that year the planet's most extraordinary year for extreme weather since reliable global upper-air data began in the late 1940s. Never in my 30 years as a meteorologist have I witnessed a year like 2010--the astonishing number of weather disasters and unprecedented wild swings in Earth's atmospheric circulation were like nothing I've seen. The pace of incredible extreme weather events in the U.S. over the past few months have kept me so busy that I've been unable to write-up a retrospective look at the weather events of 2010. But I've finally managed to finish, so fasten your seat belts for a tour through the top twenty most remarkable weather events of 2010. At the end, I'll reflect on what the wild weather events of 2010 and 2011 imply for our future.

Earth's hottest year on record
Unprecedented heat scorched the Earth's surface in 2010, tying 2005 for the warmest year since accurate records began in the late 1800s. Temperatures in Earth's lower atmosphere also tied for warmest year on record, according to independent satellite measurements. Earth's 2010 record warmth was unusual because it occurred during the deepest solar energy minimum since satellite measurements of the sun began in the 1970s. Unofficially, nineteen nations (plus the the U.K.'s Ascension Island) set all-time extreme heat records in 2010. This includes Asia's hottest reliably measured temperature of all-time, the remarkable 128.3°F (53.5°C) in Pakistan in May 2010. This measurement is also the hottest reliably recorded temperature anywhere on the planet except for in Death Valley, California. The countries that experienced all-time extreme highs in 2010 constituted over 20% of Earth's land surface area.


Figure 1. Climate Central and Weather Underground put together this graphic showing the nineteen nations (plus one UK territory, Ascension Island) that set new extreme heat records in 2010.

Most extreme winter Arctic atmospheric circulation on record; "Snowmageddon" results
The atmospheric circulation in the Arctic took on its most extreme configuration in 145 years of record keeping during the winter of 2009 - 2010. The Arctic is normally dominated by low pressure in winter, and a "Polar Vortex" of counter-clockwise circulating winds develops surrounding the North Pole. However, during the winter of 2009 - 2010, high pressure replaced low pressure over the Arctic, and the Polar Vortex weakened and even reversed at times, with a clockwise flow of air replacing the usual counter-clockwise flow of air. This unusual flow pattern allowed cold air to spill southwards and be replaced by warm air moving poleward. Like leaving the refrigerator door ajar, the Arctic "refrigerator" warmed, and cold Arctic air spilled out into "living room" where people live. A natural climate pattern called the North Atlantic Oscillation (NAO), and its close cousin, the Arctic Oscillation (AO) were responsible. Both of these patterns experienced their strongest-on-record negative phase, when measured as the pressure difference between the Icelandic Low and Azores High.

The extreme Arctic circulation caused a bizarre upside-down winter over North America--Canada had its warmest and driest winter on record, forcing snow to be trucked in for the Winter Olympics in Vancouver, but the U.S. had its coldest winter in 25 years. A series of remarkable snow storms pounded the Eastern U.S., with the "Snowmageddon" blizzard dumping more than two feet of snow on Baltimore and Philadelphia. Western Europe also experienced unusually cold and snowy conditions, with the UK recording its 8th coldest January. A highly extreme negative phase of the NAO and AO returned again during November 2010, and lasted into January 2011. Exceptionally cold and snowy conditions hit much of Western Europe and the Eastern U.S. again in the winter of 2010 - 2011. During these two extreme winters, New York City recorded three of its top-ten snowstorms since 1869, and Philadelphia recorded four of its top-ten snowstorms since 1884. During December 2010, the extreme Arctic circulation over Greenland created the strongest ridge of high pressure ever recorded at middle levels of the atmosphere, anywhere on the globe (since accurate records began in 1948.) New research suggests that major losses of Arctic sea ice could cause the Arctic circulation to behave so strangely, but this work is still speculative.


Figure 2. Digging out in Maryland after "Snowmageddon". Image credit: wunderphotographer chills.

Arctic sea ice: lowest volume on record, 3rd lowest extent
Sea ice in the Arctic reached its third lowest areal extent on record in September 2010. Compared to sea ice levels 30 years ago, 1/3 of the polar ice cap was missing--an area the size of the Mediterranean Sea. The Arctic has seen a steady loss of meters-thick, multi-year-old ice in recent years that has left thin, 1 - 2 year-old ice as the predominant ice type. As a result, sea ice volume in 2010 was the lowest on record. More than half of the polar icecap by volume--60%--was missing in September 2010, compared to the average from 1979 - 2010. All this melting allowed the Northwest Passage through the normally ice-choked waters of Canada to open up in 2010. The Northeast Passage along the coast of northern Russia also opened up, and this was the third consecutive year--and third time in recorded history--that both passages melted open. Two sailing expeditions--one Russian and one Norwegian--successfully navigated both the Northeast Passage and the Northwest Passage in 2010, the first time this feat has been accomplished. Mariners have been attempting to sail the Northwest Passage since 1497, and have failed to accomplish this feat without an icebreaker until the 2000s. In December 2010, Arctic sea ice fell to its lowest winter extent on record, the beginning of a 3-month streak of record lows. Canada's Hudson Bay did not freeze over until mid-January of 2011, the latest freeze-over date in recorded history.


Figure 3. The Arctic's minimum sea ice extent for 2010 was reached on September 21, and was the third lowest on record. Image credit: National Snow and Ice Data Center.

Record melting in Greenland, and a massive calving event
Greenland's climate in 2010 was marked by record-setting high air temperatures, the greatest ice loss by melting since accurate records began in 1958, the greatest mass loss of ocean-terminating glaciers on record, and the calving of a 100 square-mile ice island--the largest calving event in the Arctic since 1962. Many of these events were due to record warm water temperatures along the west coast of Greenland, which averaged 2.9°C (5.2°F) above average during October 2010, a remarkable 1.4°C above the previous record high water temperatures in 2003.


Figure 4. The 100 square-mile ice island that broke off the Petermann Glacier heads out of the Petermann Fjord in this 7-frame satellite animation. The animation begins on August 5, 2010, and ends on September 21, with images spaced about 8 days apart. The images were taken by NASA's Aqua and Terra satellites.

Second most extreme shift from El Niño to La Niña
The year 2010 opened with a strong El Niño event and exceptionally warm ocean waters in the Eastern Pacific. However, El Niño rapidly waned in the spring, and a moderate to strong La Niña developed by the end of the year, strongly cooling these ocean waters. Since accurate records began in 1950, only 1973 has seen a more extreme swing from El Niño to La Niña. The strong El Niño and La Niña events contributed to many of the record flood events seen globally in 2010, and during the first half of 2011.


Figure 5. The departure of sea surface temperatures from average at the beginning of 2010 (top) and the end of 2010 (bottom) shows the remarkable transition from strong El Niño to strong La Niña conditions that occurred during the year. Image credit: NOAA/NESDIS.

Second worst coral bleaching year
Coral reefs took their 2nd-worst beating on record in 2010, thanks to record or near-record warm summer water temperatures over much of Earth's tropical oceans. The warm waters caused the most coral bleaching since 1998, when 16 percent of the world's reefs were killed off. "Clearly, we are on track for this to be the second worst (bleaching) on record," NOAA coral expert Mark Eakin in a 2010 interview. "All we're waiting on now is the body count." The summer 2010 coral bleaching episodes were worst in the Philippines and Southeast Asia, where El Niño warming of the tropical ocean waters during the first half of the year was significant. In Indonesia's Aceh province, 80% of the bleached corals died, and Malaysia closed several popular dive sites after nearly all the coral were damaged by bleaching. In some portions of the Caribbean, such as Venezuela and Panama, coral bleaching was the worst on record.


Figure 6. An example of coral bleaching that occurred during the record-strength 1997-1998 El Niño event. Image credit: Craig Quirolo, Reef Relief/Marine Photobank, in Climate, Carbon and Coral Reefs

Wettest year over land
The year 2010 also set a new record for wettest year in Earth's recorded history over land areas. The difference in precipitation from average in 2010 was about 13% higher than that of the previous record wettest year, 1956. However, this record is not that significant, since it was due in large part to random variability of the jet stream weather patterns during 2010. The record wetness over land was counterbalanced by relatively dry conditions over the oceans.


Figure 7. Global departure of precipitation over land areas from average for 1900 - 2010. The year 2010 set a new record for wettest year over land areas in Earth's recorded history. The difference in precipitation from average in 2010 was about 13% higher than that of the previous record wettest year, 1956. Image credit: NOAA's National Climatic Data Center.

Amazon rainforest experiences its 2nd 100-year drought in 5 years
South America's Amazon rainforest experienced its second 100-year drought in five years during 2010, with the largest northern tributary of the Amazon River--the Rio Negro--dropping to thirteen feet (four meters) below its usual dry season level. This was its lowest level since record keeping began in 1902. The low water mark is all the more remarkable since the Rio Negro caused devastating flooding in 2009, when it hit an all-time record high, 53 ft (16 m) higher than the 2010 record low. The 2010 drought was similar in intensity and scope to the region's previous 100-year drought in 2005. Drought makes a regular appearance in the Amazon, with significant droughts occurring an average of once every twelve years. In the 20th century, these droughts typically occurred during El Niño years, when the unusually warm waters present along the Pacific coast of South America altered rainfall patterns. But the 2005 and 2010 droughts did not occur during El Niño conditions, and it is theorized that they were instead caused by record warm sea surface temperatures in the Atlantic.

We often hear about how important Arctic sea ice is for keeping Earth's climate cool, but a healthy Amazon is just as vital. Photosynthesis in the world's largest rainforest takes about 2 billion tons of carbon dioxide out of the air each year. However, in 2005, the drought reversed this process. The Amazon emitted 3 billion tons of CO2 to the atmosphere, causing a net 5 billion ton increase in CO2 to the atmosphere--roughly equivalent to 16 - 22% of the total CO2 emissions to the atmosphere from burning fossil fuels that year. The Amazon stores CO2 in its soils and biomass equivalent to about fifteen years of human-caused emissions, so a massive die-back of the forest could greatly accelerate global warming.


Figure 8. Hundreds of fires (red squares) generate thick smoke over a 1000 mile-wide region of the southern Amazon rain forest in this image taken by NASA's Aqua satellite on August 16, 2010. The Bolivian government declared a state of emergency in mid-August due to the out-of-control fires burning over much of the country. Image credit: NASA.

Global tropical cyclone activity lowest on record
The year 2010 was one of the strangest on record for tropical cyclones. Each year, the globe has about 92 tropical cyclones--called hurricanes in the Atlantic and Eastern Pacific, typhoons in the Western Pacific, and tropical cyclones in the Southern Hemisphere. But in 2010, we had just 68 of these storms--the fewest since the dawn of the satellite era in 1970. The previous record slowest year was 1977, when 69 tropical cyclones occurred world-wide. Both the Western Pacific and Eastern Pacific had their quietest seasons on record in 2010, but the Atlantic was hyperactive, recording its 3rd busiest season since record keeping began in 1851. The Southern Hemisphere had a slightly below average season. The Atlantic ordinarily accounts for just 13% of global cyclone activity, but accounted for 28% in 2010--the greatest proportion since accurate tropical cyclone records began in the 1970s.

A common theme of many recent publications on the future of tropical cyclones globally in a warming climate is that the total number of these storms will decrease, but the strongest storms will get stronger. For example, a 2010 review paper published in Nature Geosciences concluded that the strongest storms would increase in intensity by 2 - 11% by 2100, but the total number of storms would fall by 6 - 34%. It is interesting that 2010 saw the lowest number of global tropical cyclones on record, but an average number of very strong Category 4 and 5 storms (the 25-year average is 13 Category 4 and 5 storms, and 2010 had 14.) Fully 21% of 2010's tropical cyclones reached Category 4 or 5 strength, versus just 14% during the period 1983 - 2007. Most notably, in 2010 we had Super Typhoon Megi. Megi's sustained winds cranked up to a ferocious 190 mph and its central pressure bottomed out at 885 mb on October 16, making it the 8th most intense tropical cyclone in world history. Other notable storms in 2010 included the second strongest tropical cyclone on record in the Arabian Sea (Category 4 Cyclone Phet in June), and the strongest tropical cyclone ever to hit Myanmar/Burma (October's Tropical Cyclone Giri, an upper end Category 4 storm with 155 mph winds.)


Figure 9. Visible satellite image of Tropical Cyclone Phet on Thursday, June 3, 2010. Record heat over southern Asia in May helped heat up the Arabian Sea to 2°C above normal, and the exceptionally warm SSTs helped fuel Tropical Cyclone Phet into the second strongest tropical cyclone ever recorded in the Arabian Sea. Phet peaked at Category 4 strength with 145 mph winds, and killed 44 people and did $700 million in damage to Oman. Only Category 5 Cyclone Gonu of 2007 was a stronger Arabian Sea cyclone.

A hyperactive Atlantic hurricane season: 3rd busiest on record
Sea surface temperatures that were the hottest on record over the main development region for Atlantic hurricanes helped fuel an exceptionally active 2010 Atlantic hurricane season. The nineteen named storms were the third most since 1851; the twelve hurricanes of 2010 ranked second most. Three major hurricanes occurred in rare or unprecedented locations. Julia was the easternmost major hurricane on record, Karl was the southernmost major hurricane on record in the Gulf of Mexico, and Earl was the 4th strongest hurricane so far north. The formation of Tomas so far south and east so late in the season (October 29) was unprecedented in the historical record; no named storm had ever been present east of the Lesser Antilles (61.5°W) and south of 12°N latitude so late in the year. Tomas made the 2010 the 4th consecutive year with a November hurricane in the Atlantic--an occurrence unprecedented since records began in 1851.


Figure 10. Hurricane Earl as seen from the International Space Station on Thursday, September 2, 2010. Image credit: NASA astronaut Douglas Wheelock.

A rare tropical storm in the South Atlantic
A rare tropical storm formed in the South Atlantic off the coast of Brazil on March 10 - 11, and was named Tropical Storm Anita. Brazil has had only one landfalling tropical cyclone in its history, Cyclone Catarina of March 2004, one of only seven known tropical or subtropical cyclones to form in the South Atlantic, and the only one to reach hurricane strength. Anita of 2010 is probably the fourth strongest tropical/subtropical storm in the South Atlantic, behind Hurricane Catarina, an unnamed February 2006 storm that may have attained wind speeds of 65 mph, and a subtropical storm that brought heavy flooding to the coast of Uruguay in January 2009. Tropical cyclones rarely form in the South Atlantic Ocean, due to strong upper-level wind shear, cool water temperatures, and the lack of an initial disturbance to get things spinning (no African waves or Intertropical Convergence Zone.)


Figure 11. Visible satellite image of the Brazilian Tropical Storm Anita.

Strongest storm in Southwestern U.S. history
The most powerful low pressure system in 140 years of record keeping swept through the Southwest U.S. on January 20 - 21, 2010, bringing deadly flooding, tornadoes, hail, hurricane force winds, and blizzard conditions. The storm set all-time low pressure records over roughly 10 - 15% of the U.S.--southern Oregon, California, Nevada, Arizona, and Utah. Old records were broken by a wide margin in many locations, most notably in Los Angeles, where the old record of 29.25" set January 17, 1988, was shattered by .18" (6 mb). The record-setting low spawned an extremely intense cold front that swept through the Southwest. Winds ahead of the cold front hit sustained speeds of hurricane force--74 mph--at Apache Junction, 40 miles east of Phoenix, and wind gusts as high as 94 mph were recorded in Ajo, Arizona. High winds plunged visibility to zero in blowing dust on I-10 connecting Phoenix and Tucson, closing the Interstate.


Figure 12. Ominous clouds hover over Arizona's Superstition Mountains during Arizona's most powerful storm on record, on January 21, 2010. Image credit: wunderphotographer ChandlerMike.

Strongest non-coastal storm in U.S. history
A massive low pressure system intensified to record strength over northern Minnesota on October 26, 2010, resulting in the lowest barometric pressure readings ever recorded in the continental United States, except for from hurricanes and nor'easters affecting the Atlantic seaboard. The 955 mb sea level pressure reported from Bigfork, Minnesota beat the previous low pressure record of 958 mb set during the Great Ohio Blizzard of January 26, 1978. Both Minnesota and Wisconsin set all time low pressure readings during the October 26 storm, and International Falls beat their previous low pressure record by nearly one-half inch of mercury--a truly amazing anomaly. The massive storm spawned 67 tornadoes over a four-day period, and brought sustained winds of 68 mph to Lake Superior.


Figure 13. Visible satellite image of the October 26, 2010 superstorm taken at 5:32pm EDT. At the time, Bigfork, Minnesota was reporting the lowest pressure ever recorded in a U.S. non-coastal storm, 955 mb. Image credit: NASA/GSFC.

Weakest and latest-ending East Asian monsoon on record
The summer monsoon over China's South China Sea was the weakest and latest ending monsoon on record since detailed records began in 1951, according to the Beijing Climate Center. The monsoon did not end until late October, nearly a month later than usual. The abnormal monsoon helped lead to precipitation 30% - 80% below normal in Northern China and Mongolia, and 30 - 100% above average across a wide swath of Central China. Western China saw summer precipitation more than 200% above average, and torrential monsoon rains triggered catastrophic landslides that killed 2137 people and did $759 million in damage. Monsoon floods in China killed an additional 1911 people, affected 134 million, and did $18 billion in damage in 2010, according to the WHO Collaborating Centre for Research on the Epidemiology of Disasters (CRED). This was the 2nd most expensive flooding disaster in Chinese history, behind the $30 billion price tag of the 1998 floods that killed 3656 people. China had floods in 1915, 1931, and 1959 that killed 3 million, 3.7 million, and 2 million people, respectively, but no damage estimates are available for these floods.


Figure 14. Paramilitary policemen help evacuate residents from Wanjia village of Fuzhou City, East China's Jiangxi province, June 22, 2010. Days of heavy rain burst the Changkai Dike of Fu River on June 21, threatening the lives of 145,000 local people. Image credit: Xinhua.

No monsoon depressions in India's Southwest Monsoon for 2nd time in 134 years
The Southwest Monsoon that affects India was fairly normal in 2010, bringing India rains within 2% of average. Much of the rain that falls in India from the monsoon typically comes from large regions of low pressure that form in the Bay of Bengal and move westwards over India. Typically, seven of these lows grow strong and well-organized enough to be labelled monsoon depressions, which are similar to but larger than tropical depressions. In 2010, no monsoon depressions formed--the only year besides 2002 (since 1877) that no monsoon depressions have been observed.

The Pakistani flood: most expensive natural disaster in Pakistan's history
A large monsoon low developed over the Bay of Bengal in late July and moved west towards Pakistan, creating a strong flow of moisture that helped trigger the deadly Pakistan floods of 2010. The floods were worsened by a persistent and unusually-far southwards dip in the jet stream, which brought cold air and rain-bearing low pressure systems over Pakistan. This unusual bend in the jet stream also helped bring Russia its record heat wave and drought. The Pakistani floods were the most expensive natural disaster in Pakistani history, killing 1985 people, affecting 20 million, and doing $9.5 billion in damage.


Figure 15. Local residents attempt to cross a washed-out road during the Pakistani flood catastrophe of 2010. Image credit: Pakistan Meteorology Department.

The Russian heat wave and drought: deadliest heat wave in human history
A scorching heat wave struck Moscow in late June 2010, and steadily increased in intensity through July as the jet stream remained "stuck" in an unusual loop that kept cool air and rain-bearing low pressure systems far north of the country. By July 14, the mercury hit 31°C (87°F) in Moscow, the first day of an incredible 33-day stretch with a maximum temperatures of 30°C (86°F) or higher. Moscow's old extreme heat record, 37°C (99°F) in 1920, was equaled or exceeded five times in a two-week period from July 26 - August 6 2010, including an incredible 38.2°C (101°F) on July 29. Over a thousand Russians seeking to escape the heat drowned in swimming accidents, and thousands more died from the heat and from inhaling smoke and toxic fumes from massive wild fires. The associated drought cut Russia's wheat crop by 40%, cost the nation $15 billion, and led to a ban on grain exports. The grain export ban, in combination with bad weather elsewhere in the globe during 2010 - 2011, caused a sharp spike in world food prices that helped trigger civil unrest across much of northern Africa and the Middle East in 2011. At least 55,000 people died due to the heat wave, making it the deadliest heat wave in human history. A 2011 NOAA study concluded that "while a contribution to the heat wave from climate change could not be entirely ruled out, if it was present, it played a much smaller role than naturally occurring meteorological processes in explaining this heat wave's intensity." However, they noted that the climate models used for the study showed a rapidly increasing risk of such heat waves in western Russia, from less than 1% per year in 2010, to 10% or more per year by 2100.


Figure 16. Smoke from wildfires burning to the southeast of Moscow on August 12, 2010. Northerly winds were keeping the smoke from blowing over the city. Image credit: NASA.

Record rains trigger Australia's most expensive natural disaster in history
Australia's most expensive natural disaster in history is now the Queensland flood of 2010 - 2011, with a price tag as high as $30 billion. At least 35 were killed. The Australian Bureau of Meteorology's annual summary reported, "Sea surface temperatures in the Australian region during 2010 were the warmest value on record for the Australian region. Individual high monthly sea surface temperature records were also set during 2010 in March, April, June, September, October, November and December. Along with favourable hemispheric circulation associated with the 2010 La Niña, very warm sea surface temperatures contributed to the record rainfall and very high humidity across eastern Australia during winter and spring." In 2010, Australia had its wettest spring (September - November) since records began 111 years ago, with some sections of coastal Queensland receiving over 4 feet (1200 mm) of rain. Rainfall in Queensland and all of eastern Australia in December was the greatest on record, and the year 2010 was the rainiest year on record for Queensland. Queensland has an area the size of Germany and France combined, and 3/4 of the region was declared a disaster zone.


Figure 17. The airport, the Bruce Highway, and large swaths of Rockhampton, Australia, went under water due to flooding from the Fitzroy River on January 9, 2011. The town of 75,000 was completely cut off by road and rail, and food, water and medicine had to be brought in by boat and helicopter. Image credit: NASA.

Heaviest rains on record trigger Colombia's worst flooding disaster in history
The 2010 rainy-season rains in Colombia were the heaviest in the 42 years since Colombia's weather service was created and began taking data. Floods and landslides killed 528, did $1 billion in damage, and left 2.2 million homeless, making it Colombia's most expensive, most widespread, and 2nd deadliest flooding disaster in history. Colombia's president Juan Manuel Santos said, "the tragedy the country is going through has no precedents in our history."


Figure 18. A daring rescue of two girls stranded in a taxi by flash flood waters Barranquilla, northern Colombia on August 14, 2010.

Tennessee's 1-in-1000 year flood kills 30, does $2.4 billion in damage
Tennessee's greatest disaster since the Civil War hit on May 1 - 2, 2010, when an epic deluge of rain brought by an "atmospheric river" of moisture dumped up to 17.73" of rain on the state. Nashville had its heaviest 1-day and 2-day rainfall amounts in its history, with a remarkable 7.25" on May 2, breaking the record for most rain in a single day. Only two days into the month, the May 1 - 2 rains made it the rainiest May in Nashville's history. The record rains sent the Cumberland River in downtown Nashville surging to 51.86', 12' over flood height, and the highest level the river has reached since a flood control project was completed in the early 1960s. At least four rivers in Tennessee reached their greatest flood heights on record. Most remarkable was the Duck River at Centreville, which crested at 47', a full 25 feet above flood stage, and ten feet higher than the previous record crest, achieved in 1948.


Figure 19. A portable classroom building from a nearby high school floats past submerged cars on I-24 near Nashville, TN on May 1, 2010. One person died in the flooding in this region of I-24. Roughly 200 - 250 vehicles got submerged on this section of I-24, according to wunderphotographer laughingjester, who was a tow truck operator called in to clear out the stranded vehicles.

When was the last time global weather was so extreme?
It is difficult to say whether the weather events of a particular year are more or less extreme globally than other years, since we have no objective global index that measures extremes. However, we do for the U.S.--NOAA's Climate Extremes Index (CEI), which looks at the percentage area of the contiguous U.S. experiencing top 10% or bottom 10% monthly maximum and minimum temperatures, monthly drought, and daily precipitation. The Climate Extremes Index rated 1998 as the most extreme year of the past century in the U.S. That year was also the warmest year since accurate records began in 1895, so it makes sense that the warmest year in Earth's recorded history--2010--was also probably one of the most extreme for both temperature and precipitation. Hot years tend to generate more wet and dry extremes than cold years. This occurs since there is more energy available to fuel the evaporation that drives heavy rains and snows, and to make droughts hotter and drier in places where storms are avoiding. Looking back through the 1800s, which was a very cool period, I can't find any years that had more exceptional global extremes in weather than 2010, until I reach 1816. That was the year of the devastating "Year Without a Summer"--caused by the massive climate-altering 1815 eruption of Indonesia's Mt. Tambora, the largest volcanic eruption since at least 536 A.D. It is quite possible that 2010 was the most extreme weather year globally since 1816.

Where will Earth's climate go from here?
The pace of extreme weather events has remained remarkably high during 2011, giving rise to the question--is the "Global Weirding" of 2010 and 2011 the new normal? Has human-caused climate change destabilized the climate, bringing these extreme, unprecedented weather events? Any one of the extreme weather events of 2010 or 2011 could have occurred naturally sometime during the past 1,000 years. But it is highly improbable that the remarkable extreme weather events of 2010 and 2011 could have all happened in such a short period of time without some powerful climate-altering force at work. The best science we have right now maintains that human-caused emissions of heat-trapping gases like CO2 are the most likely cause of such a climate-altering force.

Human-caused climate change has fundamentally altered the atmosphere by adding more heat and moisture. Observations confirm that global atmospheric water vapor has increased by about 4% since 1970, which is what theory says should have happened given the observed 0.5°C (0.9°F) warming of the planet's oceans during the same period. Shifts of this magnitude are capable of significantly affecting the path and strength of the jet stream, behavior of the planet's monsoons, and paths of rain and snow-bearing weather systems. For example, the average position of the jet stream retreated poleward 270 miles (435 km) during a 22-year period ending in 2001, in line with predictions from climate models. A naturally extreme year, when embedded in such a changed atmosphere, is capable of causing dramatic, unprecedented extremes like we observed during 2010 and 2011. That's the best theory I have to explain the extreme weather events of 2010 and 2011--natural extremes of El Niño, La Niña and other natural weather patterns combined with significant shifts in atmospheric circulation and the extra heat and atmospheric moisture due to human-caused climate change to create an extraordinary period of extreme weather. However, I don't believe that years like 2010 and 2011 will become the "new normal" in the coming decade. Many of the flood disasters in 2010 - 2011 were undoubtedly heavily influenced by the strong El Niño and La Niña events that occurred, and we're due for a few quiet years without a strong El Niño or La Niña. There's also the possibility that a major volcanic eruption in the tropics or a significant quiet period on the sun could help cool the climate for a few years, cutting down on heat and flooding extremes (though major eruptions tend to increase drought.) But the ever-increasing amounts of heat-trapping gases humans are emitting into the air puts tremendous pressure on the climate system to shift to a new, radically different, warmer state, and the extreme weather of 2010 - 2011 suggests that the transition is already well underway. A warmer planet has more energy to power stronger storms, hotter heat waves, more intense droughts, heavier flooding rains, and record glacier melt that will drive accelerating sea level rise. I expect that by 20 - 30 years from now, extreme weather years like we witnessed in 2010 will become the new normal.

Finally, I'll leave you with a quote from Dr. Ricky Rood's climate change blog, in his recent post,Changing the Conversation: Extreme Weather and Climate: "Given that greenhouse gases are well known to hold energy close to the Earth, those who deny a human-caused impact on weather need to pose a viable mechanism of how the Earth can hold in more energy and the weather not be changed. Think about it."

Reposted from Weather Underground by Dr Jeff Masters, Director of Meteorology.

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Comments 301 to 350 out of 422:

  1. Thanks Albatross for the feedback on Xie. Rest assured that I do not get any papers from the denialsphere or especially "the list". On the contrary, if a paper is on "the list" I will look for a different one. I agree with the basic thrust of your comments, particularly that this is an academic look at hail and got a few things wrong about the real phenomenon. Also, like the paper in 290, does not address severe versus ordinary hail.
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  2. Oh and Eric,

    Maybe you can help Norman identify the two myths in the Wikipedia article on hail at #287.
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  3. Eric @301,

    Just to be sure, my comment at 302 was directed at your name's sake, Eric Red.
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  4. Albatross,

    First off, I do not consider Wikipedia to be a valid scientific source - sorry Norman. That does not mean that it does not contain useful information, just that it is not proof-read for errors. Increases in low level moisture will enhance hail production. Decreases in wind shear will diminish the growth of hailstones. Yes, these are generalization, but as you mentioned, both of these are requirements for the production of large diameter hailstones. I am not disagreeing with your equations, but the conditions in a severe thunderstorm are so chaotic, that the equations may be too simple.

    I do like your approach to severe weather better than others on this thread. Looking at the occurrance and intensity of hail, tornadoes, and wind gusts are better indicators than rainfall amounts.

    When have I ever said that I was not interested in the physics? I suggest you re-read that thread for the proper context.
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    Response:

    [DB] "When have I ever said that I was not interested in the physics?"

    Perhaps you forgot this (and previous), from the Lessons from Past Climate Predictions: Syun-Ichi Akasofu thread:

    Eric the Red at 06:55 AM on 7 July 2011

    My mistake on the wood for trees index. Sorry. However, if his predictions are based on CRU, then the comparison must be made to CRU, whether or not you agree with the dataset. The point is, it is still too soon to evaluate his prediction, as it is still in line with the temperature measurements. If the temperature does not fall in the next few years, then lambaste him.

    Dana, what does the term physics doesn't matter have to do with this?

    Emphasis added for clarity.

  5. DB @ 283

    "Until you can mount a position of substance based on sound analysis and rooted in physical processes, which you have not yet demonstrated to date, others would be well advised to ignore your contrarian efforts to further derail this thread."

    You are an excellent moderator and I do understand your reasoning. Perhaps many climate scientists are of the thinking that Global warming will lead to more severe weather events in the future (intensity, duration and return frequency) and my view, without any formal training in climatology or having the knowledge of all the mathematics and equations used in climate models, must be supported by ample evidence before anyone should take the time to consider it.

    My argument is that Global warming (as it is currently taking place, Poles are warming faster than Equator) would decrease the temperature gradient and lead to actually less severe weather patterns in the future. Tom Curtis and post 292 also seems to express this conclusion. Some Climate models may be predicting and increase in severe weather because of Global warming.

    I will attempt with more data to demonstrate why I feel my view is valid and at least should be considered and that experts in the field are stating the same things I have been. If I do not satisfy your request for sound analysis rooted in physical processes then I believe it is time for me to discontinue posting until I can update my knowledge. I will not be performing the math on this post as others have already accomplished this. I will include some quotes that do support my view and see how it goes from there.

    Rather than use my own mind with its limited knowledge and resources on the topic I will let the experts do the talking.

    Strong Jet Stream and April Tornadoes.

    "The persistent presence of a strong jet stream over the South is the main culprit in why this April has been such a terrible month for tornadoes."

    From another article:

    " Jet Stream
    A region of increased wind speeds.
    Typically found above the largest horizontal temperature gradient.
    Stronger in the winter when the temperature gradients are the largest."

    Sourc article of above quote.

    A simple jet stream someone modeled based upon the tempertature gradient of the poles to the tropics, adjust temperature gradient to see what happens to wind speed.

    Simple model demonstrating temperature gradient and wind speed.


    "In addition to the seasonal effects directly
    caused by changes in solar radiation, there is also
    an important effect that is caused by the lag in
    heating and cooling of the atmosphere as a whole.
    The result is a predominance of cool air over
    warming land in the spring, and warm air over
    cooling surfaces in the fall. Thus, the steepest
    lapse rates frequently occur during the spring,
    whereas the strongest inversions occur during fall
    and early winter."

    Source article for above quote.

    "Steep lapse rates were found to be associated with most major tornado outbreaks by Craven (2000)."

    and "The superposition of steep lapse rates and low level moisture was shown to be ideal for severe storm/tornado formation."

    Source article for above quote.


    "4. Temperature Gradient
    Temperature gradient plays a very important
    role in the development of midlatitude cyclones. In
    fact, the reason why midlatitude storms are more
    frequent during the winter is partly because of the
    strong equator-pole temperature difference. A twolayer
    quasi-geostrophic baroclinic instability model,
    also known as the Phillips model (Vallis 2006, p.
    271), is used to empirically evaluate the effect of
    temperature gradient on the propagation speed and
    growth rate."

    Source article for above quote.

    I have attempted to demonstrate, with numerous links, that my objection to the Conclusion: Global Warming=Climate Change=Increased extreme weather is based not on my own opinion but one that is shared by experts in the field. A decreasing temperature gradient (AGW theory conclusion that poles warm faster than equator) will decrease the strength of the jet stream (which is linked to severe storms), reduce steepness of lapse rate.

    As Eric the Red stated in post 294 "Global warming would increase the warm, moist air component, but decrease the cold, dry air. The net result is probably more rain, but less severe storms."
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  6. I don't know, Norman. I'm a little mixed on this issue. I'm still learning the basics of atmospheric dynamics. Consider how warming might increase the height of the tropopause and also increase the allowable height of storm cells. Has any work been done on average storm height trend?

    I will point out that I recently experienced the strongest straight-line storm winds I've ever experienced (in 45 years) in Missouri: 60 mph sustained with 80 mph gusts in a ten mile-wide line. Widespread F1 damage, with spots of F2. No deaths, but 44 hours without power. Roughly 1 in 3 houses lost a tree in a community of 17k (I lost a medium silver maple, grumble).
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  7. Norman @305,

    Have you managed to identify the two myths being perpetuated on the hail Wikipedia page?

    You also continue to plow forward and ignore the body of science/evidence. You ignored your claim concerning the freezing level as demonstrated by the example I gave @ #269 and brought to your attention at #287. You ignore the fact that is the very same example for Kansas that I gave earlier there was no marked upper-level jet present (winds near the tropopause were <50 kts). Yet, there was giant hail observed at the surface. The jet can and does affect storm severity, but it is clearly not the silver bullet that you make it out to be. And you keep ignoring the findings made in the papers that I provided many posts ago now, as well as what Tom Curtis provided at #246, so I guess they bear repeating, again:

    Trapp et al. (2007) found that:

    "We use global climate models and a high-resolution regional climate model to examine the larger-scale (or “environmental”) meteorological conditions that foster severe thunderstorm formation. Across this model suite, we find a net increase during the late 21st century in the number of days in which these severe thunderstorm environmental conditions (NDSEV) occur. Attributed primarily to increases in atmospheric water vapor within the planetary boundary layer, the largest increases in NDSEV are shown during the summer season, in proximity to the Gulf of Mexico and Atlantic coastal regions."

    Note: They state that "Herein, the number of days on which CAPE × S06 [0-6 km vertical wind shear] locally exceeds an empirical threshold based on Brooks et al. (5) is denoted by NDSEV. Hence, NDSEV is used as a proxy to the number of days on which thunderstorms could form locally and potentially produce significant surface winds, hail, and/or tornadoes. "

    That is Trapp et al. (2007) determined that the number of days in which severe thunderstorm environmental conditions (NDSEV) occur is expected to increase despite the anticipated slight decrease in the 0-6 km wind shear.

    Del Genio et al. (2007, GRL) found that:
    "For the western United States, drying in the warmer climate reduces the frequency of lightning-producing storms that initiate forest fires, but the strongest storms occur 26% more often. For the central-eastern United States, stronger updrafts combined with weaker wind shear suggest little change in severe storm occurrence with warming, but the most severe storms occur more often."

    So your persistent claim that the upper-level jet will weaken which means fewer severe storms has been shown to be demonstrably wrong. Also, you are in essence arguing a strawman-- no one is claiming that the vertical wind shear will stay the same or increase, none is denying the paradigm which states that vertical wind shear is oftentimes important for severe thunderstorm formation. Yet, the decrease (not cessation or dramatic reduction)
    of vertical wind shear is compensated or perhaps even swamped by the increase in buoyancy, and the maximum updraft velocity is proportional to buoyancy.

    I have also pointed out previously that the role of low-level vertical wind shear is especially important for severe and tornado potential-- look up 0-3 km SRH, 0-3 km EHI etc., and that the Great Plains low-level jet (which is not a baroclinic jet) can provide ample low-level vertical wind shear, as well as the return flow of moisture in the boundary layer from the Gulf of Mexico.

    You say:
    "A decreasing temperature gradient (AGW theory conclusion that poles warm faster than equator) will decrease the strength of the jet stream (which is linked to severe storms), reduce steepness of lapse rate."

    On the first at count we all agree, but I am not sure how you arrived at the conclusion that the environmental lapse rate will decrease with AGW. Regardless, Trapp et al and other researchers' work would have taken any such reduction in the environmental lapse rate in their calculations of CAPE. So you are arguing another strawman there...

    You say,
    "If I do not satisfy your request for sound analysis rooted in physical processes then I believe it is time for me to discontinue posting until I can update my knowledge."

    As a scientist actively working in this particular field, my suggestion would be to encourage you to do so before posting further, and to please actually read the multitude of references provided to you here. Like others have noted I suspect that you are having trouble grasping the science on this topic because you have some mental blocks impeding your willingness to accept the science and what the science is suggesting.
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  8. Norman @305:

    "My argument is that Global warming (as it is currently taking place, Poles are warming faster than Equator) would decrease the temperature gradient and lead to actually less severe weather patterns in the future. Tom Curtis and post 292 also seems to express this conclusion."


    On the contrary. While I agreed with your premise I disagreed with your conclusion as being too simplistic. I am sorry if I was insufficiently clear.

    To be more specific, as the climate warms, we would expect tornadoes to arrive more frequently earlier in the spring. But earlier in the spring there is a greater north-south differential in temperature. Therefore, while the north-south differential in any given month will decline, with global warming the north-south temperature differential may actually be greater at the time when tornadoes form in the future.

    To illustrate this, consider average temperature differential between Austin and Chicago in degrees centigrade for the months March, April and May (Average temperature for Austin given in brackets):

    March 13.4 degrees C (16.1 degrees C)
    April 11.1 degrees C (19.5 degrees C)
    May 9.5 degrees C (24 degrees C)

    Now, suppose that as a result of global warming, conditions in the mid-west are such that, excluding the north-south temperature differential, conditions in April are as good for spawning tornadoes as they are currently in May. In that case, in order for the temperature differential to have decreased in those circumstances, temperatures in Chicago will have to have risen by 1.6 degrees C more than those in Austin. If temperature differential aside, conditions in March become as good as current conditions in April for spawning tornadoes, unless temperatures in Chicago have risen at least more than 2.3 degrees C those in Austin, the north-south temperature differential will be greater for those conditions than they are at present.

    That means if increased temperature is the only thing driving early tornado formation, temperatures in Chicago have to rise 67% faster than those in Austin for March, and 29% faster for April. Given that they are only separated by 12 degrees of Latitude, that is a big difference in change in temperature.

    And of course, temperature is not the only driver of tornadoes, with increased humidity also likely to result in earlier tornadoes. So even at the simplest plausible level of analysis (which will no doubt leave Albatross groaning) there is no basis for an assumption that global warming will decrease either the frequency or intensity of tornadoes, and several factors which suggest it will do the opposite. Further, detailed modelling shows that it is likely to increase the frequency, and possibly the intensity rather than the reverse.
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  9. Tom @289,

    Sorry for the delay in responding to your questions.

    Re "My question is, to what extent do these regions owe there intense thunderstorms to their peculiar geography, and to what extent to their mid-latitude location? Or perhaps better, are storms more frequent and intense in the tropics except under unusual geographical circumstances which promote thunderstorm and tornado formation?"

    Geography is important. For example, thunderstorms (including severe thunderstorms) in Canada, USA and Argentina are found in the lee (downwind side) of mountain ranges. In Argentina, they have a similar low-level barrier jet to the Great Plains low-level jet, with the South American low-level jet pulling down moisture from the Amazon (kinda like the forest equivalent of the Gulf of Mexico). Anyhow, this particular aspect is something that I am not very familiar with, at least not off the top of my head, and it is not really germane to the discussion here. Also, we are by and large in good agreement on the pertinent details concerning severe storms.

    Re "I continue to believe the lightning map gives a reasonable representation of thunderstorm frequency and intensity."

    I wholeheartedly agree about the frequency, intensity is more tricky, especially if by "intensity" one means tornadoes and severe hail. One has to be cautious when using lightning occurrence or frequency as a proxy for severe weather-- just because a region had a lot of lighting activity one month or year, does not necessarily imply that there was a higher incidence of severe thunderstorms (at least using the criteria for severe thunderstorms used by most met agencies/services). There is ongoing work in using various lightning metrics to infer storm severity, but the results so far concerning flash rate in a cell versus cell severity are not entirely clear. Goodman (1999) found evidence of jumps in flash rates preceding the occurrence of severe weather in Florida storms, others have found that the ratio of positive to negative cloud-to-ground flashes can be important discriminator for hailstorms (e.g., Liu et al. 2009). With many countries now having the luxury of sophisticated lightning detection networks that record the amperage, polarity etc. of the strikes, and some progress is being made.

    IMHO, lightning data is underutilized and much is still to be learned by looking at lightning data more closely.
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  10. Albatross,

    Question: Does an expansion/growth of the Hadley Cells have an impact on this? Does it move certain weather patterns further north (or south in the SH) with the edges of the growing cells? Does this in turn potentially result in a greater temperature gradient, or the delivery of more moisture to a location with a more severe gradient, or the movement of the relevant weather patterns to a more or less geographically fertile region for severe storm generation?
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  11. A new paper out by Durack and Wijffels (2010) that corroborates other research that the planet's hydrological cycle is amplifying as the planet warms. They conclude:

    "Qualitatively, the observed global multidecadal salinity changes are thus consonant with both broad-scale surface warming and the amplification of the global hydrological cycle."

    So another independent line of evidence. More here.
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  12. Sphaerica @310,

    Large-scale atmospheric dynamic is not my area of expertise, so I am reticent to talk though my hat about it. What I do think is that as climate zones shift in response to the warming and changes in moisture content, that such changes will affect thunderstorm and perhaps even severe thunderstorm occurrence.

    IIRC the Canadian Arctic is already experiencing an increase in thunderstorm activity in response to the warming and moistening up there. So it will be interesting to see what happens down the road.
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  13. Albatross @ 307

    "Have you managed to identify the two myths being perpetuated on the hail Wikipedia page?"

    Wikipedia quote from your ealier post.
    "Unlike ice pellets, hail stones are layered and can be irregular and clumped together. Hail is composed of transparent ice or alternating layers of transparent and translucent ice at least 1 millimetre (0.039 in) thick, which are deposited upon the hail stone as it cycles through the cloud, suspended aloft by air with strong upward motion until its weight overcomes the updraft and falls to the ground".

    I guess one would be the formation aspect of hail. Ice is not deposited on hailstones to make them grow. Supercooled water is one of the processes. I guess the biggest myth is that the weight of the stone overcomes the updraft and falls to the ground. This explanation is dominatnt on articles on hail. I answer would be that hail falls when it encounters the downdraft (falling with the rain) or it can be blown over the downdraft and fall before the rain.

    Hail formation and why it falls.

    And this one:
    Hail over the downdraft.

    Hail likely in the downdraft with the rain.
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  14. Albatross @ 307

    "So your persistent claim that the upper-level jet will weaken which means fewer severe storms has been shown to be demonstrably wrong. Also, you are in essence arguing a strawman-- no one is claiming that the vertical wind shear will stay the same or increase, none is denying the paradigm which states that vertical wind shear is oftentimes important for severe thunderstorm formation. Yet, the decrease (not cessation or dramatic reduction)
    of vertical wind shear is compensated or perhaps even swamped by the increase in buoyancy, and the maximum updraft velocity is proportional to buoyancy."

    The question to you would be why do severe storms diminish in July and August even though that air is the warmest and contains the most amount of water vapor (fuel for storms)?

    That is the point I was trying to make with all the material I linked to. Graphs with tornadoes. Now I have one with hail (critical it is the largest hail which is only produced in the most severe thunderstorms).

    Graph of hailstone number per month.

    This graph comes from this link:
    Article with hail graphs.

    In the United States the most severe storms occur April, May, June and diminish in July and August (tornadoes, hail, rain, lightning). This is the time of year that the temperature gradient between North and South is greater than July, August (it is even greater in the winter but the air does not contain the moisture and lift to generate severe storms). But the July and August air have the most energy.
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  15. Albatross @ 307

    Breaking down your post so each individual post does not get too long.

    Me:
    "A decreasing temperature gradient (AGW theory conclusion that poles warm faster than equator) will decrease the strength of the jet stream (which is linked to severe storms), reduce steepness of lapse rate."

    "On the first at count we all agree, but I am not sure how you arrived at the conclusion that the environmental lapse rate will decrease with AGW. Regardless, Trapp et al and other researchers' work would have taken any such reduction in the environmental lapse rate in their calculations of CAPE. So you are arguing another strawman there..."

    From my post at 305:
    "In addition to the seasonal effects directly
    caused by changes in solar radiation, there is also
    an important effect that is caused by the lag in
    heating and cooling of the atmosphere as a whole.
    The result is a predominance of cool air over
    warming land in the spring, and warm air over
    cooling surfaces in the fall. Thus, the steepest
    lapse rates frequently occur during the spring,
    whereas the strongest inversions occur during fall
    and early winter."

    Logic I use, if the steepest lapse rates frequently occur during spring (reason being the air was cooled during the winter months and then rapidly warming air from the increased solar insolation in the south brings this warm air into the region that still has colder air above, buoyancy). Then they are not so frequent in the summer. Something must be changing. The upper layers of atmpsphere are warming as well as the lower by convection and storms. The colder air aloft (accumulated during winter) is being turned over and the steep lapse rate is decreasing, the air is not as buoyant and will not produce near the number of severe storms as in the spring...even though the air has much more energy and water vapor.

    Some evidence of this I have been working on.

    Severe Tornado graph.

    Sinde you work in the field, am I correct is stating that severe tornadoes are a valid proxy for determining relative number of severe storms? Only the most severe thunderstorms are capable of producing strong tornadoes. These storms usually have very strong winds, heavy rain and hail and are likely to cause property damage in areas where no tornado touches down.

    I just picked a few so it is not a full scientific study but I also have limited time. I try to do the best I can in the time I have available.

    1974 was big tornado year.

    GISS map March 1974.

    The big tornado outbreak took place in early april. Relative to a normal temperature gradient (all white) this graph shows a stronger than normal temp gradient and it is oriented so the warm air is in the south (moisture fuel) and the coler air in the North.

    GISS April 1974.

    Still a strong temperature gradient and very warm ocean water.

    I certainly do understand your point that the production of a storm cannot come under some sweeping generalization. Storm formation is a complex beast as I learned in reading about CAPE here.

    CAPE article.

    Air can be a very complex structure. It can form layers where a parcel will be buoyant and then other layers where this is not the case. Also some layers can be wet or dry and wind direction can vary. So what drives an individual storm can be quite complex. But overall patterns do exist which favor storm formation. My contention is that a strong temperature gradient is an important factor (but it has to have the correct orientation. It the north is warm and south is cooler, opposite gradient, it seems to suppress storm frequency).

    GISS April 2011.

    Large tempertature gradient in this graph. Very warm gulf. My understanding is that the warm southern air moves up North when a low pressure system moves across the country (counterclockwise spin pulls this air north and pulls the colder northern air behind it). It also pulls the cold northern air down over the southern regions. The sun rapidly warms the ground and the warm moist air will rise rapidly in this cooler air (very steep lapse rate) powerful updrafts, hail, tornadoes and strong winds with heavy rain.

    1987 was a very low year for tornadoes. What was the pattern this season?

    GISS 1987 graph in March.

    Warm over the whole US with cooler air to the south (opposite gradient).

    GISS 1987 graph of April.

    There is some colder air far north but the warmer air is all the way into Canada and there is still the opposite gradient (cool air south and warmer air north)

    GISS May 1987.

    GISS June 1987.
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  16. Albatross @ 307

    I am not stating my view of weather is correct or the right one. I think it has potential since it seems to have some support from the available evidence.

    April, May, and June generally have the highest frequency of severe weather. The air has far less energy in April and May than July and August. July and August months are the pattern I see with Global warming. With poles warming much faster than the equator, the temperature differential will lessen. More water will be evaporated in the air with the potential to produce more severe storms but I still believe that the lapse rate will weaken and you will not have the buoyant air that exists in April, May and June. Why do I feel the lapse rate will weaken (relative to now). The arctic air will not be as cold so it will not be as cold aloft when the warm moist air from the south is pulled up by a low pressure system.

    From a previous Skeptical Science article

    Skeptical Science link.

    "One last point from this CCC analysis of temperatures: it's also worth noting the magnitude of recent Arctic warming. The slope of the 30-year trend in this region is 5 to 6 C/century -- a rate of warming that's much higher than the rest of the world. Given the magnitude of this Arctic amplification, it's not surprising that sea ice is declining and Greenland is losing ice."

    The temperature gradient determines the pressure gradient (warm air rises...low pressure and cold air sinks high pressure. The situation is opposite above the pressure systems. A surface high pressure is a low pressure aloft).
    The pressure gradient determines the wind strength and mixing of air. A temperature gradient where cold air above is necessary to generate buoyancy (without this you have stable air and no storms, just puffy cumulus clouds, no vertical development). If the arctic air is relatively warmer, logic follows that the air above in spring will not be as cold with global warming as it was without.
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  17. Albatross @ 307

    I am reading the articles you link to (mostly abstracts). They are predictions based upon their models about what will take place. They seem to assume the lapse rate will stay the same and the warmer wetter air will have more energy to generate more intense storms. I do not understand the logic they used to arrive at that conclusion. That is part of what I am questioning. I am asking why they believe more storms will take place in the future with a warming climate when it does not happen now in the world of today. If all it took was warmer and wetter air then July and August would be the months with the most severe weather (at least in the US, other countries would have different seasons). This is not the case.
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  18. Tom Curtis @219

    Munich Re never did reply to my query. But I did find this article while looking around for other items.

    Note graph on page 4 of the article. Notice that the rate of tornadoes is level (similar to the earthquakes in Munich Re). But hail and wind go up drastically. The writers of the article believe as I do. Undereporting and increase in population of previously unpopulated areas are mainly responsible for the drastic increase (and not extreme changes in weather frequency as you currently believe).

    "Figure 2. Number of Reported Microevents, 1974 - 2003
    In addition to inconsistencies over time, there are also geographical differences in the level of
    reporting. In particular, there is a positive correlation between the number of reported events and
    population density, suggesting that many events may have gone undetected in areas where the
    population is low."

    Graph of weather related events.
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  19. Tom Curtis @ 308

    "To be more specific, as the climate warms, we would expect tornadoes to arrive more frequently earlier in the spring. But earlier in the spring there is a greater north-south differential in temperature. Therefore, while the north-south differential in any given month will decline, with global warming the north-south temperature differential may actually be greater at the time when tornadoes form in the future"

    I am not sure why you would conclude this. Why would the north-south temperature differential be greater when the poles are warming much faster than the equator?

    From your post at 292 "Therefore we would expect the forces driving climate towards equilibrium would be stronger in winter and spring than in summer in the American mid-west.

    Despite this, thunderstorms and tornadoes are generally associated with warmer weather. The logical conclusion is that they will be more frequent in spring than in summer, ie, when it is warm enough for super cells to form, but before the strong north south temperature gradient dissipates."

    Tornadoes are more frequent in spring than summer. So it seems you were agreeing with my position.

    My brain dead. I can't follow the logic of what you are stating with your post about tornadoes arriving earlier and the temperature of Chicago. "That means if increased temperature is the only thing driving early tornado formation, temperatures in Chicago have to rise 67% faster than those in Austin for March, and 29% faster for April. Given that they are only separated by 12 degrees of Latitude, that is a big difference in change in temperature."


    "And of course, temperature is not the only driver of tornadoes, with increased humidity also likely to result in earlier tornadoes. So even at the simplest plausible level of analysis (which will no doubt leave Albatross groaning) there is no basis for an assumption that global warming will decrease either the frequency or intensity of tornadoes, and several factors which suggest it will do the opposite. Further, detailed modelling shows that it is likely to increase the frequency, and possibly the intensity rather than the reverse."

    Tom, what are those several factors which suggest it will do opposite? Modelling may show it will increase, but it is not answering why the model shows this. It seems the model is going against the observable reality. There are fewer severe storms in July and August than in April, May and June. The air is warmest and holds most water in July and August yet this fact does not lend itself to the production of severe storms. The definate thing that takes place in July and August (as you pointed out) is that pressure differential decreases so with it, pressure differential and mixing energy. The tropics have the world's most supply of warm moist air yet have less severe storms than the mid=lattitudes and the midlattitudes only have the severe weather while the cold upper air still allows buoyancy and creates explosive storms. That is whay I am missing. Why would a world where temperature differential is decreasing generate more intense weather. The logic is going against the actual world and I need to understand the flaw in my thinking. Thanks.
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  20. Norman,

    Play with this.
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  21. Norman,

    And play with this too.
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  22. Albatross @ 321

    I thank you much for these tools.
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  23. Albatross, looking at the link in 321, and comparing months in the lowest graphic, the severe reports (total) peak in May. Looking at each separately, the hail and tornadoes peak in May, but the wind peaks in July (at almost the same value as June). The distribution of reports moves north with each passing month. That would be due to a variety of factors, jets moving north, cold air disappearing to the north, warm air aloft moving north, etc.

    The link to CC will come at the edges of that pattern. I would except an earlier severe weather season further south. Also I would expect the migration of severe weather to the north to start sooner in the season. That website doesn't appear to show trends, but I also do not expect such trends for quite a few more years due to the vagaries of variability especially in the U.S. where the Pacific ocean has such a large effect.
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  24. Severe weather, indeed.

    July 5 Phoenix dust storm in pictures and with some meager NWS analysis.
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    Response:

    [DB] Welcome back; you're late.

  25. Norman @313,

    Regarding the myths--well myth may be too strong a word, perhaps misconception is more appropriate.

    You say "Ice is not deposited on hailstones to make them grow."

    While hail growth from the accretion (interception) of supercooled droplets is very important, the hail growth equations also allow for the growth of hail by intercepting ice crystals. This is especially effective during wet growth when collection efficiencies of ice onto the wet surface is quite high, but is less effective during dry growth when the collection efficiency for ice is very low.

    Anyhow, the first common misconception that I was referring to are that hailstones grow to large sized by "clumping together". While this may happen on rare occasions, it is certainly not the norm. This misunderstanding probably arises because of images like this (of the largest hailstone on record in the USA):



    Those nodes/knobs can be simulated without having to allow for hailstones "clumping together" (e.g., Lozowski et al. 1991"). They can also form when a gyrating hailstone undergoes melting (e.g., Lesins and List 1986) .

    The second misconception that I was referring to was that the layer son a hailstone form because the stone grows by undertaking repeated cycling through the updraft. Research has shown that this, while again is certainly possible, is not the norm. According to a meta analysis of Knight and Knight (2001)[Chpt. 6 in "Severe Convective Storms"]:

    "The trajectories themselves, however, are usually quite simple, given embryos to start with: single, up-and-down paths though and around the main updraft. Recycling paths are found, but not very often, and when recycling trajectories are found the decision of what part belongs to the embryo stage can be quite arbitrary"

    And

    "...they [hailstone layers] do not carry a message of drastic, repeated vertical excursions, but if anything the opposite: of relatively simple growth trajectories, often with most of the growth within a fairly narrow altitude and temperature ranges.
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  26. #314 Norman at 14:59 PM on 9 July, 2011

    You ask "The question to you would be why do severe storms diminish in July and August even though that air is the warmest and contains the most amount of water vapor (fuel for storms)?"

    Norman, you may not realize it but your question is quite ridiculous in the context of what the research shows and int he context of what I said-- your question makes no sense in relation to what I said. You are conflating the more subtle changes by month or by seasons with the quite drastic changes observe during the course of the spring and summer (March-August). This is similar to stating that most locations experience marked temperature changes between winter and summer each year, so a few degrees of AGW is nothing to be concerned about. The studies I am referring (see Trapp et al. 2007 kindly provided by Tom Curtis here) to look at the changes between the mean MAM (March, April, May) conditions for 1962-1989 and how mean MAM conditions might look in the future, 2072–2099.



    I urge you to read Trapp et al. (2007) and Trapp et al. (2009) in their entirety. They are not talking about the "new May" becoming similar to the present July, for example. One has to compare apples with apples. This is a very important point, and one that you repeatedly keep on missing. I do not know whether this is intentional on your part, or simply because you are so far out of your depth on this complex issue.

    Marsh et al. (2009) made similar findings for Europe concerning the potential for an increase in severe thunderstorm episodes over Europe. They found that:

    "Preliminary comparisons of the CCSM3's 21st century simulation under the IPCC's A2 emissions scenario to the 20th century simulation indicated a slight increase in mean CAPE in the cool season and a slight decrease in the warm season and little change in mean wind shear. However, there was a small increase in favorable severe environments for most locations resulting from an increase in the joint occurrence of high CAPE and high deep layer shear."

    They add that:
    "At best, one can say that the CCSM3 predicts the number of favorable severe environments will increase in a future characterized by anthropogenic warming."

    You say "In the United States the most severe storms occur April, May, June and diminish in July and August (tornadoes, hail, rain, lightning)"

    Funny how we can look at the same graphs and arrive at different conclusions. According to the database compiled by Schaefer and Edwards, they say "May and June are the peak months for the occurrence of tornadoes and large hail. In contrast, July and June are the top months for wind storms." April and July are the next highest for all tornadoes, respectively.
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  27. Albatross,

    Your last two paragraphs above seem to be saying the same thing, rather than being contrasting. In fact, if you eliminate April from the first paragraph and wind from the second, they are the same. If May becomes similar to July, then severe storms should diminish in May and June, with July and August diminishing further.
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  28. Norman at 16:03 PM on 9 July, 2011

    You say "I am reading the articles you link to (mostly abstracts). They are predictions based upon their models about what will take place. They seem to assume the lapse rate will stay the same and the warmer wetter air will have more energy to generate more intense storms. I do not understand the logic they used to arrive at that conclusion. That is part of what I am questioning."

    Actually, Tom Curtis provided you links to two of the seminal papers, not just abstracts. This glib dismissal of the science based on your incorrect and incomplete understanding of the science left me speechless. They did not "assume the lapse rate will stay the same", your claim in this regard is demonstrably false (see below), yet it seems to be your reason for dismissing their findings as you then go on to argue the strawman that you created. This is nonsense Norman. In fact, your whole premise for creating your argument about lapse rates just shows how out of your depth you are and how little you understand the science-- in fact, so confuse dis your reasoning that I had a hard time figuring out what you were trying to say. You also seem to be confusing meridional gradients with vertical temperature gradients (i.e., lapse rates), are far too focused on the role of differential temperature advection in creating steep lapse rates (forgetting the role of the Mexican plateau and strong diabatic heating in generating steep lapse rates over the southern Great Plains, for example) and under the misconception that Arctic air is somehow stored in the upper-levels of the troposphere. Yet, you seem to feel compelled to argue the experts in this field and dismiss their findings equipped only with your preconceived and misguided notions and Google.

    From Trapp et al. (2007):
    "The two quantitative measures of CAPE and S06 were computed at each model grid point, for each day during the RF and A2 periods, using the RegCM3 output at 00 UTC."
    To calculate CAPE they used the vertical profiles of temperature (the RegCM3 model has 18 levels in the vertical), which would by default include information about the vertical lapse rates. The profiles were not constant, nor were the lapse rates.

    From Marsh et al. (2009):
    "The atmospheric portion of the CCSM3, the Community Atmospheric Model 3 (CAM3), is a spectral model with 85- wavenumber triangular truncation (approximately 1.4° at the
    equator) in the horizontal with 26 terrain-following hybrid levels in the vertical. The numerical scheme used in the CAM3 is an Eulerian spectral transform with semi-Langrangian tracer transport and semi-implicit leapfrog time stepping (Collins et al., 2006). CAM3's vertical resolution contains 4 levels below 850 hPa and 13 levels above 200 hPa (topmost being 2.2 hPa)."


    Again, the temperature profiles were not constant/specified. Again, any changes in the lapse rates would be reflected in the CAPE values.

    Please do not respond to me Norman, I and others have wasted hours of our lives drafting these posts and trying to explain the science to you, all to no avail it seems. I'm done here.

    PS: I have no idea what compels people to think that climate science and complex issue such as severe storms are an open house to speculation and 'debunking'; that equipped with Google and their misguided and shallow understanding that the science and physics can be dimissed or overthrown. It is infuriating to say the least. I am pretty well educated, yet have no intent or drive to argue with an engineer or oncologist
    that they have gotten something wrong because I happen to think differently, or because a result is not intuitive to me (nor should it be, I am not an expert in that field) and have access to Google. So it blows my mind to see self-professed 'skeptics' on the internet passionately arguing the physics and science on all aspects on climate science (oceanography, radiative transfer, physics, modelling etc.). Worse yet, when presented with the physics and facts, they then contort all kinds of excuses to dismiss them rather than using it as an opportunity to learn.
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  29. EricRed @327,

    You, like Norman, seem intent on missing the point entirely-- I even bolded the text @326 and reproduced the figure from Trapp et al. (2007). You somehow missed this from my post @ 326:

    "You are conflating the more subtle changes by month or by seasons with the quite drastic changes observe during the course of the spring and summer (March-August). This is similar to stating that most locations experience marked temperature changes between winter and summer each year, so a few degrees of AGW is nothing to be concerned about. The studies I am referring (see Trapp et al. 2007 kindly provided by Tom Curtis here) to look at the changes between the mean MAM (March, April, May) conditions for 1962-1989 and how mean MAM conditions might look in the future, 2072–2099."

    They are comparing apples with apples, you are not. You and Norman are in fact hopelessly confused on this.

    Also, it is obvious that you have either not read Trapp et al. (2007, 2009), or you did read it but are incapable of following the science (and there is no shame in that, we can't all be experts at everything or even most things). I'll give you the same advice that I gave Norman:

    "I urge you to read Trapp et al. (2007) and Trapp et al. (2009)in their entirety."

    Otherwise it is very clear that you are pontificating and talking through your hat, and I have no intention of wasting any more of my time arguing in circles with you either. You both keep repeating the same incorrect notions, sadly that doesn't make them any more correct or real.

    PS: In retrospect asking you to read the paper when you are not an expert in the field and have preconceived ideas may not help. then again, Tom Curtis is not an expert in this field, yet he managed to correctly interpret the science in the papers.

    PPS: The point of me quoting Schaefer and Edwards was to demonstrate that Norman had not accurately reflected their findings.
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  30. Albatross,

    Trapp has concluded that CAPE is the dominant factor in determing supercell formation. That theory is not shared by all. Others maintain that vertical shear is most important. What is agreed upon is that when both are high, severe thunderstorm formation, and possible tornadic activity are most likely.

    We disagree on the same point. Currently, I am leaning towards wind shear being most important, but have not ruled out CAPE being most important. I am basing this on current studies which show available moisture increasing throughout the summer months, but wind shear decreasing, and consequently, severe storms decreasing as the summer progresses.
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  31. For those still following this thread,

    The skeptics are misrepresenting Trapp et al's findings. Nowhere in their 2007 and 2009 papers do they even use the word "supercell". So no, they do not hypothesize that CAPE is the dominant factor in determining supercell formation as is claimed @330. Besides, severe weather can be caused by other types of thunderstorms (e.g., multicell, MCSs before they go upscale, squall lines, derechos etc.).

    Moreover, Trapp et al. state very clearly that they are identifying "severe thunderstorm environmental conditions". Their motivation for using the product of CAPE and 0-6 km wind shear is solidly rooted in theory and has been corroborated by empirical studies comparing proximity soundings to severe events.

    An interesting tidbit. Brooks et al. (2003) looked at the magnitude of the vector wind difference between the surface and 6 km (m s^-1) and CAPE (J kg^-1) for all reanalysis soundings associated with severe thunderstorms in US for 1997–1999. They found that as CAPE increased, the 0-6 km wind shear required to produce significant severe storms (i.e., hail of 5 cm or greater in diameter, wind gusts of 120 km hr^-1 or greater, or a tornado of F2 intensity or greater) decreased. The graph looks similar to the one below (sorry I have been unable to identify the source, nor find a suitable graphic that is not embedded in a PDF):


    [Source]

    Why this is, is an interesting story....but now I really do have to take care of some work.
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  32. Eric the Red @ 330

    From Albatross post 328 "PS: I have no idea what compels people to think that climate science and complex issue such as severe storms are an open house to speculation and 'debunking'; that equipped with Google and their misguided and shallow understanding that the science and physics can be dimissed or overthrown."

    I have taken Albatross's criticism to heart and continued to study the issue and gain knowledge about the subject.

    The more I study the more it seems I may be correct in my view that the current warming scenerio, Poles warming faster than Equator would push weather away from severe storms.

    I am not sure you wish to discuss it further. If you do I can start adding links and some ideas. Let me know if you have any interest in this.
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  33. Norman... Can we ask where you are gathering your information? With Google I can prove that magnets cure arthritis and jet vapor trails are a plot to... do something nefarious.

    The idea is to identify solid research based on real science.
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  34. Rob Honeycutt @ 333

    Here is one presentation of effects of Global Warming.

    " Warmer temperature  more moisture can exist in air
     Condensation of water vapor causes a huge amount of
    heating
     Moisture causes lapse rate to be
    smaller
     In other words: latent heating causes temperatures to
    cool less quickly with height"

    Source for above quote.

    The difference between an air parcel's lapse rate and the environmental lapse rate is how CAPE is determined. If the environmental lapse rate is getting smaller because of the heating caused by latent heat of condensed water vapor, why would storms intensify under global warming?

    From Trapp et al. (2009) "[18] The severe-thunderstorm forcing increases in time in spite of the decreases in vertical wind shear (Figure 1d), and because of compensating increases in CAPE (Figure 1e). Potential contributors to CAPE include the temperature lapse
    rate in the middle troposphere, the boundary-layer temperature, and the boundary-layer water vapor [e.g., Brooks et al., 2003]. For the current experiments, these are listed in increasing order of importance, with essentially no longterm trend indicated in the temperature lapse rates over a 3–5 km AGL layer (not shown), and a statistically significant positive trend in specific humidity q (Figure 1f). Considerable linear correlation between changes in CAPE and changes in q (Table 1) reinforces this attribution."

    If you check up on negative lapse rate because of Global warming, the results all seem to move in the direction that the upper atmosphere will warm and the environmental lapse rate overall will be less (currently at around -7 C per 1000 meters). Yet in the Trapp et. al (2009) article the models they are using show no change in the longterm lapse rate.
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  35. Rob Honeycutt @ 333

    I still do not believe anyone has actually demonstrated why my reasoning is flawed or incorrect. It may well be as Albatross has pointed out. It is a postition that is based upon physics, however, so I would need a good reasoned response of why my thinking is not correct.

    Point. Hypothetically if all the Earth was warmed equally then the Earth would be mostly weatherless. It is the temperature gradient (both horizontal and vertical) that creates the pressure differences that drive weather and climate patterns. The AGW theory has the poles warming faster than the poles (in all the graphs it looks to be about twice as much)....

    Page 15 of this IPCC report shows the projected Global warming of various models.

    This pattern would lead the world closer to the weatherless system than the oppostite direction. So why would weather patterns intensify?

    In a two body system, it is not the temperature of a body that determines rate of heat flow, it is the difference between the two bodies. In the atmosphere, it is not the temperature of the tropics that determines wind intensity, it is the difference between tropics and poles. The gradient.

    How about two mountain river and turbulence? One river goes straight down the mountain with a large gradient difference between points on the vertical. The other winds around the mountain with very shallow gradients. Which of the two rivers will have more turbulence even though the overall graviational energy is the same.

    With Poles warming twice as fast as the equator it seems the push would be away from severity and turbulence and a push to less extremes. At least that is what my thinking sees it. I might be wrong, that is not the point. At this time I do not understand the flaw of my reasoning and would hope someone would point it out.
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  36. Norman @355:

    1) Global warming has increased the level of the tropopause. That means as air rises in thermals, it is given a gains a stronger Easterly (blowing to the west) component due to angular momentum. The air is then carried north or south, and when it returns to Earth gains a stronger Westerly (blowing to the east) component for the same reason.

    2) The Hadley cells have expanded with global warming meaning surface winds from air returning towards the Inter Tropical Convergence Zone have a stronger Easterly component due to angular momentum.

    3) The atmosphere has a greater moisture content because it is warmer,and hence rises faster in thermals, thus drawing wind in faster at the base, creating stronger local winds.

    4) The land is heating faster than the sea, resulting in stronger onshore winds.

    5) As has been explained above, the greatest temperature differential between poles and tropics is in the winter, and the least in the summer. Warmer weather can trigger storms earlier in the year when the differential is greater. This may be partly or completely compensated for by differential heating between pole and tropics, but there can be no automatic assumption that it will be.

    6) And most importantly, this general reasoning readily provided reasons to expect stronger and/or more frequent storms with global warming. Other considerations give reasons to expect less (perhaps). But general arguments like this and like yours cannot be used to make predictions. They are so vague that they cannot even definitively narrow down the sign of the predicted effect. (Actually, I think they strongly indicate stronger storms, but the reasoning is not conclusive.) To do that you need to do the mathematics, which in climate science means run the models. The models have been run and show consistently that situations favourable to storm formation will be more frequent.
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  37. This is just a little thought experiment I conjured up to demonstrate the difficulty I have with the idea that reducing the temperature gradient between poles and equator will lead to more severe weather patterns in the future.

    It may not be a valid understanding of how CAPE works, it is an attempt to demonstrate my position.

    Note: This is a simplified version of CAPE and does not reflect the complexity of real world CAPE calculations. It is a conceptualization of a point that may or may not be valid.

    Source I used for simplified CAPE calculation.

    The thought experiment involves the setting off of a hydrogen bomb in the arctic ocean to generate a large parcel of warm air in a very cold region.

    Intitial Arctic Air I am using. -10 C at surface. I am using the stantard environmental lapse rate of -7 C/1000 m
    I am running the thought experiment from the ground up to 8000 meters. The moist air warmed by the hydrogen bomb is 25 C and I am using -6 C/1000 m as the moist adiabatic lapse rate. (not a real world situation and simplified to demonstrate a point).

    All data in equation:
    Surface Arctic air: -10 C (263 K)
    Arctic air at 8000 meters (-7 C/1000 m lapse rate): -66 C (207 K)
    H-Bomb surface air: 25 C (298 K)
    H-Bomb air at 8000 meters (-6 C/1000 m lapse rate): -23 C (250 K)

    [(298-263)/263+(250-207)/207]/2(9.8)(8000)=CAPE 13367.2

    In the next calculation I will increase the polar temperature by 2 times the H-bomb temp. In this case I will not change the moist lapse rate but will in the next cycle.

    Now: Arctic Air: 0 C (10 C warmer) (273 K)
    Arctic Air at 8000 meters: (same lapse rate) -56 C (217 K)
    H-bomb air temp: 30 C (303 K)
    H-bomb air temp 8000 meters: -18 (255 K)

    [(303-273)/273+(255-217)/217]/2(9.8)(8000)=CAPE 11172.6

    A considerable drop from the 13367.2 from above.

    Even though this is a simplistic calculation. The point I am trying to demonstrate with it is that as frontal systems in the US (low pressure) (which are supposed to get weaker with global warming as the horizontal temperture gradient is reduced...I have a link above on this) pull up warm moist air from the Gulf of Mexico and pull down cold Canadian air from the North, the cold north air will be less cold in the future relative to the warm gulf air.

    Side Note on what causes instability:
    "Causes of Instability
    • Cooling of the air aloft:
    –Winds bringing in colder air (cold advection)
    – Clouds (or the air) emitting IR radiation to
    space (radiational cooling)
    • Warming of the surface air:
    – Daytime solar heating of the surface
    –Winds bringing in warm air (warm advection)
    – Air moving over a warm surface"

    Source for above quote.

    I put in this note because in order for you to have an unstable atmophere you need a source of cold air. In the future that cold air will be relatively less than now when compared to the future warm air.

    On the next calculation I am going to change the warm air lapse rate since in the Trapp articles the claim is that the change in lapse rate because of the higher moisture content of future air will be enough to overcome the loss of vertical wind shear of future atmospheric conditions.


    Arctic Air. Still 0 C
    8000 meter Arctic Air -56 (217 K) same lapse rate (but all indications suggest that the environmental lapse rate is going to change, become less as the globe warms)

    H-bomb air still 30 C
    Changed the lapse rate from -6 C/1000 m to -5 C/1000 m
    new temp at 8000 feet -10 C (reduced from -18 C above) or 263 K

    [(303-273)/273+(263-217)/217]/2(9.8)(8000)=CAPE 12617.8

    At some point the change in the moist adiabatic rate will overcome the effect of having warmer polar temperatures. If I use -4 C/1000 m the CAPE value in the above equation will exceed the 13367.2. In this situation you get CAPE of 14061.

    At this time I do not see an obvious pattern that would easily demonstrate that weather will get more severe in the future with ongoing Global Warming. It might happen but it may not. I would think it would more closely mimic the tropical type weather patterns. More rain, less severe weather.

    Again, my major point is that as the system approaches equilibrium (the gradient between the opposites is reduced, be it gravity, heat, chemicals) the intensity of reactions goes down not up.

    I may be very wrong in my thinking but it would be nice for someone to point out the flaw.
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  38. Rob Honeycutt @ 333

    I do use Google searches for information. I try to find high quality material and I adapt my choices based upon feedback to my posts. I try to use good scientific sources for my points.
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  39. Norman... Have you tried reading the research that explains why the current consensus is that a warming planet will see more extreme weather? What I get from your thinking here is that you don't understand how this works. There is certainly a lot of published research out there about why this is believed to be correct, and why it is the generally accepted thinking.

    Rather than trying to test to see if anyone here can explain it for you why not allow the published literature explain it? I believe that is the accepted procedure if you're going to study a given phenomenon. Get a clear understanding of the state of the research, then ask questions. It strikes me as difficult to form an adequate thought experiment on a complex issue if you don't have a full grasp of the full body of research.

    I recently had a number of questions about the MWP and started collecting papers and reading them. It didn't take long to realize where the limits of my understanding were and my questions were answers only after reading a few papers.
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  40. Rob Honeycutt @ 339

    It is not a lack of my understanding of "how it works" for Global warming to result in more extreme weather. I have read the peer-reviewed articles on the subject as well as other material. So far it is the same general concept. Increase in available moisture will produce air with much more latent heat. That latent heat will warm a parcel of air as it rises generating more buoyancy, faster updrafts and more moist air being drawn up in the updraft to perpetuate the cycle.

    I do understand this concept and I could agree with the conclusions if the environmental lapse rate did not change. Other material is suggesting the environmental lapse rate will be more negative with global warming (one reason is all the released latent heat from condensation will warm the mid=troposphere layers reducing the lapse rate and decreasing the buoyancy of future moist air parceles that enter this air. The steep lapse rates of the United States plains are caused by the cold northern air. This air will not be nearly as cold under global warming. That is what I attempted to demonstrate with my hypothetical H-Bomb in Arctic ocean calculations above.

    What I do not understand is why the researchers are assuming that the evironmental lapse rate will stay the same under global warming conditions. They do not explain it in the papers.

    Again from post 224 "From Trapp et al. (2009) "[18] The severe-thunderstorm forcing increases in time in spite of the decreases in vertical wind shear (Figure 1d), and because of compensating increases in CAPE (Figure 1e). Potential contributors to CAPE include the temperature lapse rate in the middle troposphere, the boundary-layer temperature, and the boundary-layer water vapor [e.g., Brooks et al., 2003]. For the current experiments, these are listed in increasing order of importance, with essentially no longterm trend indicated in the temperature lapse rates over a 3–5 km AGL layer (not shown), and a statistically significant positive trend in specific humidity q (Figure 1f). Considerable linear correlation between changes in CAPE and changes in q (Table 1) reinforces this attribution."

    This is the point I do not understand and would like some more clarification: " with essentially no longterm trend indicated in the temperature lapse rates over a 3–5 km AGL layer"

    Why woudln't the long term lapse rates change? Less cold air to move into air aloft, more heat in the air because of latent heat condensation release. With both these events taking place why do they not find a strong negative trend in the environmental lapse rate. Such a trend would suppress the severity potential of a mass of warm moist air.

    If you know an explanation I would be thankful.
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  41. Tom Curtis @ 336

    Tom, I thought angular momentum would cause a slowdown of velocity when the system expands. (like the ice skater on ice analogy. She has a certain spin speed with her arms outstreched, when she pulls her arms in her spin velocity increases to conserve angular momentum). If the Hadley cells expand then the velocity of the air would slow down to conserve angular momentum. This would also be the case with an expanding troposphere. The winds in the rotating thermals would move slower as it covers more distance.

    Your point 3) That is the basics of my line of questions. An increase in moiture of an air parcek would increase the thermal velocity of an updraft if the environmental lapse rate was unchanged, I still do not understand why the lapse rate won't change.

    Your point 4) Would this temperature gradient between sea and land be sufficient to cause wind effects that were destructive? I think there is a calculation for it.

    Your point 6) This is the big one. The climate models. They put in many mathematical formulas to arrive at their results. I still wonder why the environmental lapse rate is not shown to change in the models. This all goes back to the post Dikran Marsupial had about the double pendulum model.

    Equations for double pendulum.

    These equations will generate a model double pendulum. Will it mimic a real world pendulum? In the real world many more varialbes would effect the actual motion of the pendulum. The model can only give a general description of a "real" world double pendulum. It may match one closely or deviate at some point because of some assumptions. In the models of severe weather they have many equations and must make some assumptions.

    Here is a link:

    Climate model equation.

    Quote from article: "In Meteorology, the primitive equations are a version of the Navier-Stokes equations that describe hydrodynamical flow on the sphere . . . Thus, they are a good approximation of global atmospheric flow and are used in most atmospheric models"

    Note "good approximation"

    Also a model has to make some assumptions. Why do they assume no longterm trend in the temperature lapse rates? Makes a huge difference in what the model will come up with.

    IPCC use of models for small scale events.

    Since climate models are based upon the laws of physics they are good guides for seeing patterns but all these laws working together makes a system to complex to model completely.

    The question still is why did Trapp et al (2009) find no longterm change in lapse rate temperature?

    One scientist's view: "Global Warming One: possibility for
    further research is whether or not a significant change in normal lapse rates is an indicator of climate change.
    My hypothesis is tha twith an overall warmer climate, there
    will be a slower lapse rate."

    Article for above quote.

    If the environmental lapse rate slows enough (less temperature difference with height) it will counter any effect that can come from higher latent heat in warmer moister air.

    It seems is if there is not enough agreement on what happens to the environmental lapse rate to make the Trapp et al. (2009) study conclusive about the future of severe weather events.
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  42. Norman @341:

    1) If a spinning body extends its radius, it will slow down the spinning body. Consequently, the raising of the tropopause does indeed slow down the Earth by some imperceptibly small amount. (Or perhaps no imperceptible, they measure the length of the day very accurately these days.) But in extending the radius, the angular velocity of the outermost portion of the rotating body becomes greater.

    2) You repeatedly assert that the models do not allow for a changing environmental lapse rate. That is false. Rather, they do not program the change in lapse rate in to the model, but allow the physics to sort it out.

    3) (And this relates primarily to your 337) you assume that the environmental lapse rate for a body of dry air from the arctic will be close to that for 100% humidity (6.5). In fact it would be much closer to the dry adiabatic lapse rate of 9.8.

    This relates to one of your most bizzare assumptions, ie, that the environmental lapse rate is almost identical everywhere. The environmental lapse rate depends on a large number of local features of the atmosphere, but most importantly on the relative humidity. If a body of saturated air moves south from the Arctic and warms from 0 degrees to 10 degrees C, it will no longer be saturated, and hence its lapse rate (all else being equal) will increase substantially. The same thing will happen if it moves south and goes from 5 degrees to 15 degrees C.

    Now look at the holding capacity of water vapour in air at different temperatures:



    As you can see, an increase in temperature from 0 to 10 degrees C increases the holding capacity by about 5 grams per Kg of air. An increase from 30 to 35 degrees increases the holding capacity by nearly 10 grams. Half the temperature increase and nearly double the holding capacity increase.

    There seems to be absolutely no understanding of this difference in your models. In contrast the meteorological models that tell us CAPE will increase have this built in to their physics.

    3) Which brings us back to models, and you complete misunderstanding of what it means for a climate model to be accurate.

    Consider a double pendulum. It's state at any moment can be completely described by seven, numbers three of which are invariant. The three invariant numbers are the length of the two pendulums, and the distance from the axis at with the second pendulum is attached to the first. The variable numbers are the angle of the main pendulum arm from the vertical, the angle of the second pendulum arm to the main pendulum arm, and the angular momentum of each bob.

    Given the exact specification of each of these numbers, an ideal pendulum's behavior is deterministic but chaotic. Consequently a model of a double pendulum cannot predict the four variable values with any degree of accuracy more than a short time in the future. But what it can predict is the frequency of occurrence of particular values for the four variables, either individually or jointly.

    In view of the fact that you clearly have no idea as to what are the strengths and limitations of climate modelling, can I recommend that you start by getting an appreciation of what can, and can't be modeled in chaotic systems. You just need a PC, a double pendulum, a stroboscope, and a video camera. Run a model of the pendulum on the PC, and collect as data the frequency of particular angles of the pendulums (the first two variables). Using the strobe and camera, set the double pendulum in motion and check the frequency of the various angles. If the model is any good, and if the pendulum is any good (stable base and low friction) the frequencies should match very closely. Having done this, and having gained a true appreciation of the power and limitations of the modelling of chaotic systems, then we can discuss models.

    In the meantime you are obviously all at sea if you don't even know the meaning of "good approximation" in scientific use. FYI, Newton's laws of motion and gravity are a "good approximation" of the behavior of the solar system, yet using them the Voyager 2 space craft was launched on a fly by of four outer planets with an accuracy something like splitting a hair at 2 miles distance.
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  43. Tom Curtis @ 342

    3) for the Arctic air lapse rate. I thought it would be the dry adiabatic. But looking around for an actual number I don't think it is. Here is an actual lapse rate from Fairbanks Alaska in December.

    The explanation in reading is that Polar Arctic air starts as Polar Maratime air which is at the moist adiabatic. The air near the surface cools rapidly but the upper levels retain their original lapse rates and the air is very stable (warmer above colder below).

    Artic air lapse rate from Fairbanks Alaska.
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  44. So your "model" is that the Arctic air starts being cold and saturated, and when it moves to the mid west it is still saturated because in the Amercian Spring, it is still at winter Arctic temperatures?

    Because if it isn't, your defence of your position is not valid. And if it is, your position has refuted itself by absurdity.
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  45. Norman and Tom,

    Much of the argument comes down to the amount of moisture in the air vs. the wind shear as the dominant force in severe storms. There are several other valid poinnts put force regarding Hadley cells and temperature gradients. I have followed the links, and understand (mostly) the conclusions drawn from the various works.

    From all that I have gathered, this is still an unresolved issue. As stated earlier, I believe that the winds shear will predominant, and will decrease due to the decreasing temperature gradient (among other things). I could be wrong, and either the moisture content in the warmer air, or the changing Hadley cells will result in greater storm formation.

    Yes Norman, I find this subject quite interesting and would like to continue involvement.

    Tom, even though we disagree, I find your arguments and resources quite informative, both here and elsewhere.
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  46. Tom Curtis @ 342

    Tom, I can't agree with your statement: "1) If a spinning body extends its radius, it will slow down the spinning body. Consequently, the raising of the tropopause does indeed slow down the Earth by some imperceptibly small amount. (Or perhaps no imperceptible, they measure the length of the day very accurately these days.) But in extending the radius, the angular velocity of the outermost portion of the rotating body becomes greater."

    Quote from information on angular momentum: "This formula indicates one important physical consequence of angular momentum: because the above formula can be rearranged to give v = L/(mr) and L is a constant for an isolated system, the velocity v and the separation r are inversely correlated. Thus, conservation of angular momentum demands that a decrease in the separation r be accompanied by an increase in the velocity v, and vice versa."

    Source of above quote.
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  47. Tom Curtis @ 342

    Your countepoint 2) "You repeatedly assert that the models do not allow for a changing environmental lapse rate. That is false. Rather, they do not program the change in lapse rate in to the model, but allow the physics to sort it out."

    That is not my question. My question is why do their models not show a change in the lapse rate. Quote from Trapp et al (2009) article you and Albatross have links to.

    "For the current experiments, these are listed in increasing order of importance, with essentially no longterm trend indicated in the temperature lapse rates over a 3–5 km AGL layer (not shown),"

    Other souces are claiming Global warming would change the lapse rates in a negative way (one reason is the the mid-lattitude troposphere would be the receiver of latent heat and tend to warm). I am not stating they should put in a changed lapse rate in their model. I am asking why doesn't the model develop a changed lapse rate.
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  48. Norman @347, the following is the projected change in atmospheric temperatures for a doubling of CO2, and represents a reasonable stand in for projected changes by the end of the century:



    Three to five kilometers above ground level is approximately 700 to 500 millbars pressure, and as you can see, the maximum difference in the change in temperature for those levels is 0.8 degrees, or a 0.4 degree reduction in the lapse rate. A 0.4 degree change in the lapse rate over 100 years is a trend of 0.004 degrees change per annum, or "essentially no longterm trend".

    I note that this is the maximum possible trend, and that and that at more northerly latitudes the trend is weaker. At 30 degrees north, the trend has reduced to, at most, a change of - 0.0025 per km altitude per annum. At sixty degrees north it becomes essentially non existent, while further north it becomes positive, ie, the lapse rate increases.

    As your argument is that the cold, more northerly air coming south has a reduced lapse rate, which will result in weaker CAPE, the fact that models predict a reduction in tropical lapse rates, but an increase in Arctic lapse rates runs directly counter to your main premise. In fact, to the extent that your argument has any validity, and with that knowledge of lapse rates, you should be predicting much stronger CAPE, and hence stronger and more frequent storms.
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    Response:

    [DB] Fixed image (let me know if this was the incorrect one).  Graphic derived from http://www.skepticalscience.com/tropospheric-hot-spot-advanced.htm

  49. Tom Curtis @ 344

    Page 6-3 of this link has a comparisson of 4 different air types. One is Arctic Polar the other are moist air masses. The Arctic Polar has a similar lapse rate.

    Comparisson of different air mass lapse rates graph, very simplistic.

    Here is another paper for you to look at.

    On page 2279 of this article there is a graph of actual lapse rates of air turning into polar continetal. You can figure out the lapse rate yourself by looking at the height vs temp change. The overall temp drop is positive, the air at the top is warmer than the air at the bottom.

    If you look at day 13 of cooling. I estimate about an 11 C drop in 2250 meters of air. That would be a lapse rate of -4.8 C/1000 meters. Much less than the -9.8 dry air.

    Article with graph of Polar air lapse rates over 14 days of cooling.
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  50. Eric the Red @345:

    "As stated earlier, I believe that the winds shear will predominant, and will decrease due to the decreasing temperature gradient (among other things)."


    With all due respect, this is a fairly subtle issue and just guessing has about as much chance of being right as a coin toss. Even educated guessing is little better, and by educated in this context I mean that of experienced meteorologists immersed in the field. Until you actually run that Maths, you have no real idea of the sign of the change, let alone the magnitude. And in this context, "run the maths" means run the best models you have available.

    As it happens, the maths has been run and has come to the opposite conclusion of your relatively uninformed guess. Still, it is a subtle issue and the model may be wrong, so we look to the data. In this case the data is showing a clear trend to more tornadoes, but significant trend for the strongest categories of tornadoes. Other forms of storms also show a positive trend. In other words, both data and models agree.

    There are problems with the data, although no it is nowhere near as problematic as Norman attempts to suggest. And models are not super accurate at this style of prediction. So we may, and I hope we do, get lucky in this regard. But regardless of our hopes, the evidence points the other way. You would do well to acknowledge that and factor that into your premises in considering what is the best policy with regard to global warming.
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