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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 is one of the largest hailstones ever observed in the United States. The stone fell on June 22, 2003 in Aurora, Nebraska.
Click on image for full size
Courtesy of University Corporation for Atmospheric Research

Hail

Hail is made in a cumulonimbus cloud where ice is tossed around by the wind. The ice crystals bump into each other and stick together making larger and larger pieces of ice. Very cold water droplets in a cloud freeze onto hailstones. When these pieces become too heavy, they fall to the ground.

Most hailstones are about the size of peas. The heaviest one in the United States was the size of a cantaloupe and fell on Kansas in 1970. Large hailstones can break windows and dent cars. A farmer’s crops can be destroyed from hail in minutes. Hail is transparent or partially opaque in color.

Hailstones do not have a perfectly round shape because the warmer temperatures below a cloud cause some of the ice to melt. Hail can fall during violent thunderstorms in the summer. Even though the summer air is warm, hail can make its way to the ground as ice without melting completely if it is large enough.

Last modified July 28, 2008 by Vanessa Pearce.

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