| Subject: But, but, but -- they said SUV's were responsible. |
Author:
Curmudgeon
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Date Posted: 18:27:46 11/24/06 Fri
In reply to:
larry
's message, "Volcanic eruptions change weather patterns" on 10:29:03 11/24/06 Fri
Can I get mhy donation back?
>just when we thought we had the weather predictions
>down. a new kink comes in to play. now we have space
>weather, volcanic weather, fire weather, land mass
>change weather.
>
>Volcanic eruptions on Iceland generated a cascade of
>events that led to record low levels of water in the
>Nile River in Africa and brought famine to the region
>more than two centuries ago, a new study concludes.
>
>
>
>The findings will inform climate forecasting related
>to future volcanic activity.
>
>
>
>From June 1783 through February 1784, a series of 10
>eruptions from the Laki Craters on this European
>island in the North Atlantic changed atmospheric
>conditions in most of the Northern Hemisphere.
>
>
>
>Unusual temperature and precipitation patterns peaked
>in the summer of 1783, causing below normal rainfall
>in most of the Nile drainage basin and therefore
>record low levels in the mighty river for up to one
>year following the eruptions.
>
>
>
>When volcanic eruptions occur, large amounts of sulfur
>dioxide are released into the atmosphere. When this
>gas combines with water vapor, aerosol particles form.
>These particles reflect sunlight back to space and
>therefore cool average temperatures on Earth.
>
>
>
>Researchers used computer models to simulate how
>Iceland’s Laki eruptions affected temperature and
>rainfall levels over the stretch of land from the
>Atlantic ocean to the “horn of Africa,” known as the
>Sahel.
>
>
>
>Simulations showed that the aerosols formed by the
>eruptions cooled average temperatures in the Northern
>Hemisphere by up to 5.4 degrees Fahrenheit. Tree ring
>data in Alaska and Siberia also showed reduced growth
>during the same summer, signifying cooler than normal
>weather.
>
>
>
>The abnormally cool temperatures reduced the
>temperature difference between the land masses of
>Africa and Eurasia and their respective water masses,
>the Atlantic and Indian oceans. Typically, a sharp
>contrast in temperature between land and sea drives
>roaring monsoon winds. Monsoons are seasonal shifts in
>wind direction that signify the beginning of the rainy
>season.
>
>
>
>The lack of monsoons led to a reduction in cloud cover
>over the Sahel of Africa, southern Arabian Peninsula
>and India that summer. This caused temperatures to
>increase by as much as 3.6 degrees Fahrenheit and
>induced drought in the region. The resulting food
>shortage reduced the population of the Nile Valley by
>a sixth.
>
>
>
>"Some of the driest weather occurred over the Nile and
>Niger River watersheds," said lead author Luke Oman, a
>researcher from Rutgers University, NJ. "The relative
>lack of cloud cover and increased temperature likely
>amplified evaporation, further lessening water
>available for run-off."
>
>
>
>This dry weather corresponded with record low river
>water levels from 1783 to 1784.
>
>
>
>“These findings may help us improve our predictions of
>climate response following the next strong
>high-latitude eruption, specifically concerning
>changes in temperature and precipitation," Oman said.
>"Many societies are very dependent on seasonal
>precipitation for their livelihoods, and these
>predictions may ultimately allow communities time to
>plan for consequences, including impacts on regional
>food and water supplies."
>
>
>href="http://www.livescience.com/environment/061121_eru
>ptions_nile.html">http://www.livescience.com/environmen
>t/061121_eruptions_nile.html
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