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  • Irish Chronicles Document Links Between Volcanoes and Weather
    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong corr...Read more

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    Irish Chronicles Document Links Between Volcanoes and Weather

    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong correlation between the occurrence of volcanic eruptions and extreme cold weather in Ireland over a 1200 year period. Data analyzed in this study cover the period from 431 to 1649, during which time up to 48 volcanic eruptions are identified in Greenland ice core records through deposition of volcanic sulfate in annual layers of ice. You can find the study (open access), published on 6 June 2013 in IOP Publishing's journal Environmental Research Letters, at http://iopscience.iop.org/1748-9326/8/2/024035/article. Find out more about how volcanoes can influence climate.
  • EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US
    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, acco...Read more

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    EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US

    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young. For more information on the tornado, visit http://ow.ly/i/2hfDG.
  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
This illustration shows how a rain shadow forms on the wind-protected side of a mountain.
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Image part of the public domain

Rain Shadow

A rain shadow is a dry region of land on the side of a mountain range that is protected from winds. The protected side of a mountain range is also called the lee side or the down-wind side.

Winds carry air toward the mountain range. As the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. This side of the mountains is called the windward side, and it is where precipitation falls in the form of rain or snow. The windward side of a mountain range is moist and lush because of this precipitation.

Once the air passes over the mountain range, it moves down the other side, warms, and dries out. This dry air produces a rain shadow. Land in a rain shadow is very dry and receives much less precipitation and cloud cover than land on the windward side of the mountain range.

Rain shadow deserts can be found all over the world. Some rain shadow deserts in the United States include the dry land east of the Cascade Mountains in Washington and Oregon, and the Colorado Front Range east of the Rocky Mountains. Rain shadow deserts can be found in other areas of the world, including the Atacama Desert in Chile, which is in a rain shadow created by both the Andes Mountains and weather patterns over the Pacific Ocean.

Last modified October 17, 2008 by Becca Hatheway.

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