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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.
When the Sum warms the Earth, warm air rises into the atmosphere. As it rises, it expands and cools. Water vapor condenses out of the cool air to form a cloud.
Click on image for full size
Image Courtesy of CMMAP

Cloud Formation from Heating of the Earth's Surface

Some clouds form because of the heating of the Earth's surface. First, the Sun heats the ground, which then heats the air. As this warm air rises in the atmosphere, it expands and cools.

The cooling air can't hold as much water vapor as it was able to hold when it was warm. This extra water vapor begins to condense out of the air parcel in the form of liquid water droplets. As the air parcel rises higher and higher, it continues to expand and get cooler, and more moisture condenses out of it.

Eventually, enough moisture will condense out of the air parcel to form a cloud! The types of clouds that form from the process of surface heating are cumulonimbus (and mammatus clouds), cumulus, and stratocumulus.

When the Earth's surface cools instead or warms, fog and stratus clouds can develop.

Last modified May 21, 2009 by Becca Hatheway.

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