Dr. Jeff Masters' WunderBlog

Volcanic Winter

Posted by: Dr. Jeff Masters, 1:18 PM GMT on April 24, 2009

"The sun was dark and its darkness lasted for eighteen months; each day it shone for about four hours; and still this light was only a feeble shadow; the fruits did not ripen and the wine tasted like sour grapes." As this Michael the Syrian quote regarding the weather of 536 A.D. demonstrates, a climate catastrophe that blots out the sun can really spoil your day. Procopius of Caesarea remarked: "During this year [536 A.D.] a most dread portent took place. For the sun gave forth its light without brightness. and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear." Many documents from 535 - 536 A.D.--the time of King Arthur in Britain--speak of the terrible "dry fog" or cloud of dust that obscured the sun, causing widespread crop failures in Europe, and summer frosts, drought, and famine in China. Tree ring studies in Europe confirm several years of very poor growth around that time, and ice cores from Greenland and Antarctica show highly elevated levels of atmospheric sulfuric acid dust existed.

Though some scientists believe the climate calamity of 535-536 A.D. was due to a comet or asteroid hitting the Earth, it is widely thought that the event was probably caused by the most massive volcanic eruption of the past 1500 years. This eruption threw so much sulfur dioxide (SO2) gas into the stratosphere that a "Volcanic Winter" resulted. Sulfur dioxide reacts with water to form sulfuric acid droplets (aerosol particles), which are highly reflective and reduce the amount of incoming sunlight. The potential eruption that led to the 535 - 536 A.D. climate calamity would have likely been a magnitude 7 event on the Volcanic Explosivity Index (VEI)--a "super colossal" eruption that one can expect to occur only once every 1000 years. The Volcanic Explosivity Index is a logarithmic scale like the Richter scale used to rate earthquakes, so a magnitude 7 eruption would eject ten times more material than the two largest eruptions of the past century--the magnitude 6 eruptions of Mt. Pinatubo in the Philippines (1991) and Novarupta in Alaska (1912).

Figure 1. An 18 km-high volcanic plume from one of a series of explosive eruptions of Mount Pinatubo beginning on 12 June 1991, viewed from Clark Air Base (about 20 km east of the volcano). Three days later, the most powerful eruption produced a plume that rose nearly 40 km, penetrating well into the stratosphere. Pinatubo's sulfur emissions cooled the Earth by about 1°F (0.5°C) for 1 - 2 years. (Photograph by David H. Harlow, USGS.)

Super-colossal eruptions
There has been only one other magnitude 7 "super-colossal" eruption in the past 1500 years--the massive eruption of the Indonesian volcano Tambora in 1815. The sulfur pumped by this eruption into the stratosphere dimmed sunlight so extensively that global temperatures fell by about 2°F (1°C) for 1 - 2 years afterward. This triggered the famed Year Without a Summer in 1816. Killing frosts and snow storms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. The Tambora eruption was about 40% smaller than the 535 - 536 A.D. event, as measured by the number of sulfur aerosol particles deposited in Greenland ice cores.

In an article published in 2008 in the American Geophysical Union journal EOS, Dr. Ken Verosub of the University of California, Davis Department of Geology estimated that future eruptions capable of causing "Volcanic Winter" effects severe enough to depress global temperatures by 2°F (1°C) and trigger widespread crop failures for 1 - 2 years afterwards should occur about once every 200 - 300 years. Even a magnitude 6 eruption, such as the 1600 eruption of the Peruvian volcano Huaynaputina, can cause climatic change capable of killing millions of people. The Huaynaputina eruption is blamed for the Russian famine of 1601-1603, which killed over half a million people and led to the overthrow of Tsar Boris Godunov. Thankfully, the climatic impacts of all of these historic magnitude 6 and 7 eruptions have been relatively short-lived. After about two years, the sulfuric acid aerosol particles have settled out of the stratosphere, returning the climate to its former state.

Mega-colossal eruptions
Even more extreme eruptions have occurred in Earth's past--eruptions ten times more powerful than the Tambora eruption, earning a ranking of 8 out of 8 on the Volcanic Explosivity Index (VEI). These "mega-colossal" eruptions occur only about once every 10,000 years, but have much longer-lasting climatic effects and thus are a more significant threat to human civilization. According to the Toba Catastrophe Theory, a mega-colossal eruption at Toba Caldera, Sumatra, about 74,000 years ago, was 3500 times greater than the Tambora eruption. According to model simulations, an eruption this large can pump so much sulfur dioxide gas into the stratosphere that the atmosphere does not have the capacity to oxidize all the SO2 to sulfuric acid aerosol. The atmosphere oxidizes as much SO2 as it can, leaving a huge reservoir of SO2 in the stratosphere. This SO2 gradually reacts to form sulfuric acid as the OH radicals needed for this reaction are gradually produced. The result is a much longer-lasting climate effect than the 1 - 2 years that the magnitude 6 and 7 events of 535, 1600, 1815, and 1991 lasted. A magnitude 8 eruption like the Toba event can cool the globe for 6 - 10 years (Figure 3), which may be long enough to trigger an ice age--if the climate is already on the verge of tipping into an ice age. Rampino and Self (1992) argued that the sulfur aerosol veil from Toba was thick and long-lasting enough to cool the globe by 3 - 5°C (5 - 9°F), pushing the climate--which was already cooling and perhaps headed towards an ice age--into a full-scale ice age. They suggested that the response of Canada to the volcano played a particularly important role, with their model predicting a 12°C (22°F) reduction in summer temperatures in Canada. This would have favored the growth of the Laurentide ice sheet, increasing the reflectivity (albedo) of the Earth, reflecting more sunlight and reducing temperatures further. The controversial Toba Catastrophe Theory asserts that the resulting sudden climate change reduced the Earth's population of humans to 1,000 - 10,000 breeding pairs. More recent research has shed considerable doubt on the idea that the Toba eruption pushed the climate into an ice age, though. Oppenheimer (2002) found evidence supporting only a 2°F (1.1°C) cooling of the globe, for the 1000 years after the Toba eruption. Zielinski et al. (1996) argued that the Toba eruption did not trigger a major ice age--the eruption merely pushed the globe into a cool period that lasted 200 years. Interestingly, a previous super-eruption of Toba, 788,000 years ago, coincided with a transition from an ice age to a warm period.

Figure 2. The 100x30 square kilometer Toba Caldera is situated in north-central Sumatra around 200 km north of the Equator. It is comprised of four overlapping calderas aligned with the Sumatran volcanic chain. Repeated volcanic cataclysms culminated in the stupendous expulsion of the Younger Toba Tuff around 74,000 years ago. The lake area is 100 square kilometers. Samosir Island formed as a result of subsequent uplift above the evacuated magma reservoir. Such resurgent domes are typically seen as the concluding phase of a large eruption. Landsat Enhanced Thematic Mapper Plus (ETM+) browse images for path/row 128/58 (6 September 1999) and 129/58 (21 January 2001) from http://landsat7.usgs.gov/. Copyright USGS. Image source: Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.

Figure 3. Total mass of sulfur dioxide and sulfate aerosol in the stratosphere (heavy solid and dotted lines, respectively) modeled for a 6 petagram stratospheric injection of SO2. Observed SO2 and aerosol mass for the 1991 Pinatubo eruption are shown for comparison. The much larger amount of SO2 in the Toba simulation soaks up all available oxidants in the stratosphere leading to a much longer lifetime of SO2 and, in turn, prolonging the manufacture of sulfate aerosol. Data from Read et al. (1993) and Bekki et al. (1996). Image source: Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.

When can we expect the next mega-colossal eruption?
Given the observed frequency of one mega-colossal magnitude 8 volcanic eruption every 1.4 million years, the odds of another hitting in the next 100 years is about .014%, according to Mason et al., 2004. This works out to a 1% chance over the next 7200 years. Rampino (2002) puts the average frequency of such eruptions at once every 50,000 years--about double the frequency with which 1-km diameter comets or asteroids capable of causing a similar climatic effect hit the Earth. A likely location for the next mega-colossal eruption would be at the Yellowstone Caldera in Wyoming, which has had magnitude 7 or 8 eruptions as often as every 650,000 years. The last mega-colossal eruption there was about 640,000 years ago. But don't worry, the seismic activity under Yellowstone Lake earlier this year has died down, and the uplift of the ground over the Yellowstone caldera that was as large as 7 cm/yr (2.7 inches/yr) between 2004 - 2006 has now fallen to 4 cm/yr, according to the Yellowstone Volcano Observatory. The USGS states that "the Yellowstone volcanic system shows no signs that it is headed toward such an eruption. The probability of a large caldera-forming eruption within the next few thousand years is exceedingly low".

What would happen if a magnitude 8 mega-colossal eruption were to occur today?
If a mega-colossal eruption were to occur today, it would probably not be able to push Earth into an ice age, according to a modeling study done by Jones et al. (2005). They found that an eruption like Toba would cool the Earth by about 17°F (9.4°C) after the first year (Figure 3), and the temperature would gradually recover to 3°F (1.8°C) below normal ten years after the eruption. They found that the eruption would reduce rainfall by 50% globally for the first two years, and up to 90% over the Amazon, Southeast Asia, and central Africa. This would obviously be very bad for human civilization, with the cold and lack of sunshine causing widespread crop failures and starvation of millions of people. Furthermore, the eruption would lead to a partial loss of Earth's protective ozone layer, allowing highly damaging levels of ultraviolet light to penetrate to the surface.

Not even a mega-colossal eruption of this magnitude would stop global warming, though. The level of greenhouse gases in the atmosphere would not be affected by the volcanic eruption, and warming would resume where it left off once the stratospheric dust settled out in a decade. With civilization crippled by the disaster, greenhouse gas emissions would be substantially reduced, though (small solace!) If we really want to say goodbye to civilization, a repeat of the only magnitude 9 eruption in recorded history should do the trick--the magnitude 9.2 La Garita, Colorado blast of 27.8 million years ago (Mason et al., 2004).

Figure 4. Annual near-surface temperature anomalies for the year following a mega-colossal volcanic eruption like the Toba eruption of 74,000 years ago, if it were to occur today. Most land areas cool by 22°F (12°C) compared to average. Some areas, like Africa, cool by 29°F (16°C). Image credit: Jones, G.S., et al., 2005, "An AOGCM simulation of the climate response to a volcanic super-eruption", Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005.

What would happen if a magnitude 7 super-colossal eruption were to occur today?
An eruption today like the magnitude 7 events of 535 A.D. or 1815 would cause cause wide-spread crop failures for 1 - 2 years after the eruption. With food supplies in the world already stretched thin by rising population, decreased water availability, and conversion of cropland to grow biofuels, a major volcanic eruption would probably create widespread famine, threatening the lives of millions of people. Wars over scarce resources might result. However, society's vulnerability to major volcanic eruptions is less than it was, since the globe has warmed significantly in the past 200 years. The famines from the eruptions of 1600 and 1815 both occurred during the Little Ice Age, when global temperatures were about 1.4°F (0.8°C) cooler than today. Crop failures would not be as wide-spread with today's global temperatures, if a suer-colossal eruption were to occur. Fifty years from now, when global temperatures are expected to be at least 1°C warmer, a magnitude 7 eruption should only be able to cool the climate down to year 2009 levels.

Volcanoes also warm the climate
While volcanoes cool the climate on time scales of 1 - 2 years, they act to warm the climate over longer time scales, since they are an important source of natural CO2 to the atmosphere. Volcanoes add 0.1 - 0.3 gigatons (Gt) of carbon to the atmosphere each year, which is about 1 - 3% of what human carbon emissions to the atmosphere were in 2007, according to the Global Carbon Project. In fact, volcanoes are largely responsible for the natural CO2 in the atmosphere, and helped make life possible on Earth. Why, then, haven't CO2 levels continuously risen over geologic time, turning Earth into a steamy hothouse? In fact, CO2 levels have fallen considerably since the time of the dinosaurs--how can this be? Well, volcano-emitted CO2 is removed from the atmosphere by chemical weathering. This occurs when rain and snow fall on rocks containing silicates. The moisture and silicates react with CO2, pulling it out of the air. The carbon removed from the air is then washed into the sea, where it ends up in ocean sediments that gradually harden into rock. Rates of chemical weathering on Earth have accelerated since the time of the dinosaurs, largely due to the recent uplift of the Himalaya Mountains and Tibetan Plateau. These highlands undergo a tremendous amount of weathering, thanks to their lofty heights and the rains of the Asian Monsoon that they capture. Unfortunately, chemical weathering cannot help us with our current high levels of greenhouse gases, since chemical weathering takes thousands of years to remove significant amounts of CO2 from the atmosphere. It takes about 100,000 years for silicate weathering to remove 63% of the CO2 in the atmosphere. Thus, climate models predict that chemical weathering will solve our greenhouse gas problem in about 100,000 - 200,000 years.

For further information
PBS TV special on the 535-536 A.D. disaster.
Newspaper articles on the 535-536 A.D. disaster.
Volcanic winter article from wikipedia.
Realclimate.org has a nice article that goes into the volcano-climate connection in greater detail.

References
Bekki, S., J.A. Pyle, W. Zhong, R. Toumi, J.D. Haigh and D.M. Pyle, 1996, "The role of microphysical and chemical processes in prolonging the climate forcing of the Toba eruption", Geophysical Research Letters 23 (1996), pp. 2669-2672.

Jones, G.S., et al., 2005, "An AOGCM simulation of the climate response to a volcanic super-eruption", Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005.

Rampino, M.R., and S. Self, 1993, "Climate-volcanism feedback and the Toba eruption of 74,000 years ago", Quaternary Research 40 (1993), pp. 269-280.

Mason, B.G., D.M. Pyle, and C. Oppenheimer, 2004, "The size and frequency of the largest observed explosive eruptions on Earth", Bulletin of Volcanology" 66, Number 8, December 2004, pp 735-748.

Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.

Rampino, M.R., 2002, "Supereruptions as a Threat to Civilizations on Earth-like Planets", Icarus, 156, Issue 2, April 2002, Pages 562-569.

Read, W.G., L. Froidevaux and J.W. Waters, 1993, "Microwave Limb Sounder measurements of stratospheric SO2 from the Mt. Pinatubo eruption", Geophysical Research Letters 20 (1993), pp. 1299-1302.

Verosub, K.L., and J. Lippman, 2008, "Global Impacts of the 1600 Eruption of Peru's Huaynaputina Volcano", EOS 89, 15, 8 April 2008, pp 141-142.

Zielinski, G.A. et al., 1996, "Potential Atmospheric Impact of the Toba Mega-Eruption 71,000 Years Ago", Geophysical Research Letters, 23, 8, pp. 837-840, 1996.

Portlight moves to provide relief for South Carolina wildfires
South Carolina's biggest wildfire in more than three decades --a blaze four miles wide--destroyed dozens of homes near Myrtle Beach yesterday. Portlight Strategies, Inc. is preparing to respond to this disaster, focusing on providing drinks and sanitary products to firefighters, particularly to rural volunteer fire departments and other first responders which do not have the same resources as some of the larger paid departments. To help out, visit the Portlight South Carolina fire relief web page. Thanks!

Jeff Masters

Categories: Climate Change Volcano

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2101. muddertracker 11:37 PM GMT on April 28, 2009
Link At a large "business dinner" last night, a couple was discussing hurricane seeding and why our government should figure out a way to "kill storms." I thought seeding made a storm stronger? Anyway, I went searching and found this article. Easy reading and interesting. Member Since: August 16, 2007 Posts: 1 Comments: 2126

2102. Drakoen 11:38 PM GMT on April 28, 2009
Quoting Vortex95: lol even if I was making fun of JFV maybe I might just need it. If you keep acting like that you'll need more than that... Member Since: October 28, 2006 Posts: 57 Comments: 29010

2103. Cavin Rawlins 11:39 PM GMT on April 28, 2009
Quoting CybrTeddy: Hey Ike! Aren't you suppose to be retired? ;-) good to see you. I was watching your photo and you look very beautiful. Member Since: July 24, 2005 Posts: 407 Comments: 19076

2104. Patrap 11:39 PM GMT on April 28, 2009
The stress from the 09 Atlantic Cane Pre-Season is really..."wearing and tearing" some. Member Since: July 3, 2005 Posts: 371 Comments: 111403

2105. atmoaggie 11:46 PM GMT on April 28, 2009
Dang, I come back in here after my self-imposed one week ban on ad-revenue hits to see the same thing. This was originally due to youknowhom's blog about Arctic sea ice that included blantant cherry picking and a lot of rather bold assertions made as if He were some expert in that field. Waiting for He to predict an ice-free Arctic next year or blame the swine flu on my tailpipe (not his). Now we cover volcanoes. That is all interesting, but the assertions about global warming, CO2, etc. have struck the same chord. When the carbon budget, climatology, atmo chem and modeling communities cannot successfully account for current sources and sinks of CO2, a tropical expert making wholesale statements about it all is goofy. Please find something tropical met to discuss. How is the Sahel rainfall doing (our dust machine)? How about the advances in MJO modeling? Supplementing IR-measured SST's with microwave when there are clouds? Advances in storm surge modeling to include rainfall runoff and inundation near rivers? A thorough examination of historical proxies representing TC frequency and/or intensity? Something. Anything besides this mail-it-in what is my knee-jerk reaction to what this or that going to do to our planetary historically very low CO2 concentration (likely the limiting factor in a number of photosynthesis scenarios and other chemical processes). Serious broken record feeling. We will try to resume tropical studies in one week. Take care, all. Member Since: August 16, 2007 Posts: 6 Comments: 12461

2106. moonlightcowboy 11:47 PM GMT on April 28, 2009
Quoting hurricaneseason2006: This is the lack of humbleness I was refering to. There were others who said the same thing but there're not gloating about it. Rather arrogant if you ask me. LOL, you must not have been here very long. That's how this blog thrives - on impotent arrogance. Some wouldn't know a hailstone from flagstone; but, if you like a 3-ring circus you'll love this blog. But, hey, it's also got some really great folks here, too - folks with real weather knowledge and the social skills to go with it. I've seen bricks with more personality than some. LOL. Enjoy! I'm sure the season will rock with excitement - fasten your seatbelt and hold on for the ride! Member Since: July 9, 2006 Posts: 179 Comments: 28118

2107. IKE 11:49 PM GMT on April 28, 2009
Quoting Patrap: The stress from the 09 Atlantic Cane Pre-Season is really..."wearing and tearing" some. oh yeah... Member Since: June 9, 2005 Posts: 23 Comments: 37044

2108. moonlightcowboy 11:49 PM GMT on April 28, 2009
Quoting atmoaggie: Dang, I come back in here after my self-imposed one week ban on ad-revenue hits to see the same thing. This was originally due to youknowhom's blog about Arctic sea ice that included blantant cherry picking and a lot of rather bold assertions made as if He were some expert in that field. Waiting for He to predict an ice-free Arctic next year or blame the swine flu on my tailpipe (not his). Now we cover volcanoes. That is all interesting, but the assertions about global warming, CO2, etc. have struck the same chord. When the carbon budget, climatology, atmo chem and modeling communities cannot successfully account for current sources and sinks of CO2, a tropical expert making wholesale statements about it all is goofy. Please find something tropical met to discuss. How is the Sahel rainfall doing (our dust machine)? How about the advances in MJO modeling? Supplementing IR-measured SST's with microwave when there are clouds? Advances in storm surge modeling to include rainfall runoff and inundation near rivers? A thorough examination of historical proxies representing TC frequency and/or intensity? Something. Anything besides this mail-it-in what is my knee-jerk reaction to what this or that going to do to our planetary historically very low CO2 concentration (likely the limiting factor in a number of photosynthesis scenarios and other chemical processes). Serious broken record feeling. We will try to resume tropical studies in one week. Take care, all. Hey, Atmo. Many appreciate that sentiment. See you soon...hey, we've got a CAT 5 down in the sCarib! Don't stay gone too long! Apparently, Dr. Masters is very concerned about it. ;P Member Since: July 9, 2006 Posts: 179 Comments: 28118

2110. CaneWarning 11:53 PM GMT on April 28, 2009
Quoting atmoaggie: Dang, I come back in here after my self-imposed one week ban on ad-revenue hits to see the same thing. This was originally due to youknowhom's blog about Arctic sea ice that included blantant cherry picking and a lot of rather bold assertions made as if He were some expert in that field. Waiting for He to predict an ice-free Arctic next year or blame the swine flu on my tailpipe (not his). Now we cover volcanoes. That is all interesting, but the assertions about global warming, CO2, etc. have struck the same chord. When the carbon budget, climatology, atmo chem and modeling communities cannot successfully account for current sources and sinks of CO2, a tropical expert making wholesale statements about it all is goofy. Please find something tropical met to discuss. How is the Sahel rainfall doing (our dust machine)? How about the advances in MJO modeling? Supplementing IR-measured SST's with microwave when there are clouds? Advances in storm surge modeling to include rainfall runoff and inundation near rivers? A thorough examination of historical proxies representing TC frequency and/or intensity? Something. Anything besides this mail-it-in what is my knee-jerk reaction to what this or that going to do to our planetary historically very low CO2 concentration (likely the limiting factor in a number of photosynthesis scenarios and other chemical processes). Serious broken record feeling. We will try to resume tropical studies in one week. Take care, all. It's his blog - he can discuss whatever he wants. Member Since: April 26, 2009 Posts: 3 Comments: 3667

2111. futuremet 11:56 PM GMT on April 28, 2009
Member Since: July 19, 2008 Posts: 43 Comments: 4049

2112. TropicTraveler 11:58 PM GMT on April 28, 2009
Hi everyone from 25 degrees south latitude off the Atacama Desert area of Chili. Yesterday visited La Serena and the people there are concerned because the desert (some parts haven't had rain for over 1,000 years) is creeping south each year and within 100 years they will be in a completely rainless zone. They're doing things like putting in fog nets on hills and gathering enough fog from the Humbolt Current cold air to supply small villages. They also have some dams. Mostly their green plants live on the morning fog from the current. Fascinating area. Hard to think of no rain for a thousand years. Also got told on our ship (We're on Radiance of the Seas) that because of swine flu all of our Mexico Ports are cancelled and all RCCL ships are immediately ceasing to call at Mexican Ports. Hardship for a whole lot of people. We visit Peru next. Being in the Humbolt current is wierd. It's cool and misty every morning - never really warm. It's like rolling on a cool breeze. Our guide yesterday says they only really get good rain from El Nino years and then the dead desert near La Serena blooms. Cool Cruise and we cross the equator with ceremony before getting home. Surfmom I've seen some gorgeous surf for you the whole way - what a lot of clean, clear, freezing water. Nobody swims in it without wetsuits I guess. Bye for now from Tropic Traveler. Oh, by the way, hubby won a free cruise out of Miami in Dec by winning ships Texas Hold'm Tournament. He's walking on air! Member Since: July 24, 2007 Posts: 2 Comments: 896

2113. Drakoen 12:13 AM GMT on April 29, 2009
For what is worth the 18z NOGAPS is show a strong increase in convection around Panama at the end of the run within in broad area of low pressure: Link NOGAPS Low/Mid trop. flow Member Since: October 28, 2006 Posts: 57 Comments: 29010

2114. Cavin Rawlins 12:18 AM GMT on April 29, 2009
Member Since: July 24, 2005 Posts: 407 Comments: 19076

2115. naplesdreamer28 12:40 AM GMT on April 29, 2009
So when is Florida getting it, I know it's coming :p) Member Since: July 3, 2008 Posts: 0 Comments: 242

2116. hahaguy 12:50 AM GMT on April 29, 2009
Sure got quiet. Member Since: August 12, 2007 Posts: 2 Comments: 2838

2118. CaneAddict 12:59 AM GMT on April 29, 2009
2045. cchsweatherman 10:49 PM GMT on April 28, 2009 Lol you sound like you just read Joe Lundberg's blog (Accuweather) to come up with that summary. Member Since: October 5, 2007 Posts: 3 Comments: 2151

2119. futuremet 1:01 AM GMT on April 29, 2009
Latest Video From Futuremet Productions This is the best video I made so far It turned that my voice and accent was not the problem, it was the crappy screen recording software. The voice is a lot clear now Enjoy! Text Version Unlike diabatic processes, no external heating or cooling is involved. The thermal changes are simply occurring within the air parcel. Now, how is this possible? Does the air parcel spontaneously increases or decreases its temperature. The answer is NO! Because energy cannot be created or destroyed. Atmospheric differences in pressure are what drive adiabatic cooling and warming processes. As you may already know, cold air sinks and warm air rises, due to the fact that warmer air is less dense and more buoyant than cooler air. Adiabatic cooling process....(rising air) For example: an air parcel at 1000mb is about 25C and the air at about 700mb is about 10c. Obviously, the air at the surface will rise because it is warmer. So, what is it that actually occurs within the air parcel that causes it rise?. Because the surface temperatures are higher than the temperatures at 700b, the air molecules within the air parcel will move faster. That is because heat is energy, and this means air molecules within the air parcel at 1000mb will have higher kinetic energy than the air parcel at above at 700mb. As the air molecules move faster, they will then acquire more space, and so 1 liter of air will now occupy less air molecules than it did previously, and the pressure within the parcel decreases as a result. The air molecules within the air parcel at the surface also clash and transfer energy with one another. Now, this causes the molecules to gradually lose their kinetic energy and since heat is energy, the molecules will start to cool down. Eventually, when the rising air parcel reaches 700mb, it will replace the 700mb stable air parcel. That air parcel will then start sinking Adiabatic Warming process (sinking air) The exact opposite happens when the air sinking..... High pressure systems warm the ambient air adiabatically, because the pressure is higher, which means that the air molecules are more contracted. Synoptic scale anticyclones often help bring much warmer and nicer weather after a cold front during the winter (depends on which side of the anticyclones you are located). Now, adiabatic processes are not strictly applied to atmospheric dynamics. An inflated air balloon or a deflating tire. For example, the air within a tire cools rapidly if you deflate, because it expands and cools adiabatically as it gushes out of the tire. Thanks for watching! Member Since: July 19, 2008 Posts: 43 Comments: 4049

2120. CaneAddict 1:01 AM GMT on April 29, 2009
By the way good evening all! Member Since: October 5, 2007 Posts: 3 Comments: 2151

2121. hahaguy 1:05 AM GMT on April 29, 2009
Hey caneaddict Member Since: August 12, 2007 Posts: 2 Comments: 2838

2123. hahaguy 1:10 AM GMT on April 29, 2009
Quoting StSimonsIslandGAGuy: that post I made also summarizes my thoughts of twitter as well. Oh, can't wait for the first major twittercane to hit this year! That's why I only got a facebook page. lol Member Since: August 12, 2007 Posts: 2 Comments: 2838

2124. Ossqss 1:11 AM GMT on April 29, 2009
Quoting StSimonsIslandGAGuy: that post I made also summarizes my thoughts of twitter as well. Oh, can't wait for the first major twittercane to hit this year! I taut I taw a twittercane, sorry I could not stop my fingers. Watch out for the webicane of emails on this flu thing. People are too quick to click and gettin picked. Link Member Since: June 12, 2005 Posts: 6 Comments: 8154

2126. weatherblog 1:26 AM GMT on April 29, 2009
lol Where'd everyone go? Sure got quiet in here... JFV makes it more interesting. Nothing to talk about anymore (well, until the next GFS comes out anyways). lol Member Since: July 10, 2006 Posts: 27 Comments: 1623

2127. KEEPEROFTHEGATE (Mod) 1:27 AM GMT on April 29, 2009
well evening all back Member Since: July 15, 2006 Posts: 143 Comments: 40510

2128. Orcasystems 1:41 AM GMT on April 29, 2009
Blog Refresh Mirror Site Daily Area of Interest Click to enlarge Member Since: October 1, 2007 Posts: 77 Comments: 26077

2129. CaneWarning 1:43 AM GMT on April 29, 2009
It is quiet in here...is everyone watching American Idol? I hate that show. Member Since: April 26, 2009 Posts: 3 Comments: 3667

2130. Orcasystems 1:45 AM GMT on April 29, 2009
If a model was to hint at something hitting the Southeast coast of Florida.. it would liven up in a hurry. Member Since: October 1, 2007 Posts: 77 Comments: 26077

2131. Orcasystems 1:45 AM GMT on April 29, 2009
Quoting CaneWarning: It is quiet in here...is everyone watching American Idol? I hate that show. Hockey :) Member Since: October 1, 2007 Posts: 77 Comments: 26077

2132. CaneAddict 1:45 AM GMT on April 29, 2009
I'm here...just updating my site... Member Since: October 5, 2007 Posts: 3 Comments: 2151

2133. CaneWarning 1:48 AM GMT on April 29, 2009
Quoting Orcasystems: If a model was to hint at something hitting the Southeast coast of Florida.. it would liven up in a hurry. If the GFS is right, this place will be really busy in a few days. Member Since: April 26, 2009 Posts: 3 Comments: 3667

2134. KEHCharleston 1:49 AM GMT on April 29, 2009
BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 724 PM MDT TUE APR 28 2009 THE NATIONAL WEATHER SERVICE IN MIDLAND HAS ISSUED A * TORNADO WARNING FOR... SOUTH CENTRAL EDDY COUNTY IN SOUTHEAST NEW MEXICO... EXTREME NORTHEASTERN CULBERSON COUNTY IN SOUTHWEST TEXAS... * UNTIL 815 PM MDT/915 PM CDT/ * AT 722 PM MDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO OVER SOUTH CENTRAL EDDY COUNTY...OR 24 MILES SOUTH OF CARLSBAD...MOVING EAST AT 10 MPH. * THE TORNADO WILL AFFECT THE FOLLOWING LOCATIONS... SOUTHERN EDDY COUNTY... Member Since: August 19, 2008 Posts: 6 Comments: 2490

2135. Orcasystems 1:49 AM GMT on April 29, 2009
Quoting CaneAddict: I'm here...just updating my site... That may be the longest link expression I have ever seen. Member Since: October 1, 2007 Posts: 77 Comments: 26077

2136. Orcasystems 1:50 AM GMT on April 29, 2009
Quoting CaneWarning: If the GFS is right, this place will be really busy in a few days. I hope something happens soon... I am ready for a new blog anytime now Member Since: October 1, 2007 Posts: 77 Comments: 26077

2137. weatherblog 1:50 AM GMT on April 29, 2009
Quoting CaneWarning: It is quiet in here...is everyone watching American Idol? I hate that show. That's what I'm thinking. I think Kris is going. lol OK, anyways back to weather.. Member Since: July 10, 2006 Posts: 27 Comments: 1623

2138. CaneWarning 1:51 AM GMT on April 29, 2009
Quoting Orcasystems: That may be the longest link expression I have ever seen. I was thinking the same thing! Member Since: April 26, 2009 Posts: 3 Comments: 3667

2139. KEHCharleston 2:00 AM GMT on April 29, 2009
The following storms affected South Carolina in September 1959 - Gracie 1979 - David 1989 - Hugo 1999 - Floyd I am feeling a bit superstitious about 09/09/09 ADDENDEM: Oh... and if I am not mistaken - all were ENSO NEUTRAL with the exception of 1999 La Nina Member Since: August 19, 2008 Posts: 6 Comments: 2490

2141. KEEPEROFTHEGATE (Mod) 2:05 AM GMT on April 29, 2009
we now have 4 confirmed cases of swine flu in toronto canada Member Since: July 15, 2006 Posts: 143 Comments: 40510

2142. moonlightcowboy 2:05 AM GMT on April 29, 2009
Quoting KEHCharleston: The following storms affected South Carolina in September 1959 - Gracie 1979 - David 1989 - Hugo 1999 - Floyd I am feeling a bit superstitious about 09/09/09 ADDENDEM: Oh... and if I am not mistaken - all were ENSO NEUTRAL years Interesting. That reminds me, it'll be the 40th anniversary of Camille this year, too. Member Since: July 9, 2006 Posts: 179 Comments: 28118

2143. CybrTeddy 2:13 AM GMT on April 29, 2009
Quoting Weather456: I was watching your photo and you look very beautiful. Well uhh.. thanks. But thats my mother back in '92. My 8 year old head next to her. Member Since: July 8, 2005 Posts: 253 Comments: 20240

2144. futuremet 2:20 AM GMT on April 29, 2009
Quoting CybrTeddy: Well uhh.. thanks. But thats my mother back in '92. My 8 year old head next to her. lol Member Since: July 19, 2008 Posts: 43 Comments: 4049

2145. CaneAddict 2:30 AM GMT on April 29, 2009
Tropical Update #1 - GFS Forecasting a Tropical Storm! Member Since: October 5, 2007 Posts: 3 Comments: 2151

2146. stillwaiting 2:40 AM GMT on April 29, 2009
As I've been stating since the end of last week,I believe around may 5th we'll begin to have something to watch in EITHER the BOC or western carib,the GOM w/be very active the next 2 months,IMO....got my twitter.com/sarasotaweather....... Member Since: October 5, 2007 Posts: 20 Comments: 4970

2147. CatastrophicDL 2:41 AM GMT on April 29, 2009
Howdy all!! Member Since: September 3, 2007 Posts: 3 Comments: 1519

2149. moonlightcowboy 2:43 AM GMT on April 29, 2009
Quoting CatastrophicDL: Howdy all!! Howdy, you! :) Member Since: July 9, 2006 Posts: 179 Comments: 28118

2150. KEEPEROFTHEGATE (Mod) 2:43 AM GMT on April 29, 2009
hello cat Member Since: July 15, 2006 Posts: 143 Comments: 40510

2151. KEEPEROFTHEGATE (Mod) 2:49 AM GMT on April 29, 2009
real quiet tonight Member Since: July 15, 2006 Posts: 143 Comments: 40510

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