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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 image of the nucleus of Halley's comet comes from the Giotto spacecraft.
Click on image for full size
JPL

Halley's comet

Halley's comet is named after Edmond G. Halley who was the first to suggest that comets were natural phenomena of the solar system, in orbit around the Sun. He suggested that a certain comet was a regular visitor, returning every 76 years, and was, in fact, the same one which had been observed since 240 BC, but in particular in the years 1531, 1607, and 1682, dates which for him were recent history. In 1682 he predicted the comet would return again in 1758, and sure enough, the comet arrived in March 1759. Halley's comet made a particularly bright appearance in 1910. It also was recorded in a famous ancient tapestry after its 1066 appearance.

For hundreds of years humankind has wondered what the nucleus of Halley's comet was really like. This wonderful picture from the Giotto spacecraft gives us the answer. In this picture, the Sun is on the left. Three jets can be seen blowing molecules toward the Sun. A crater can also be seen in the middle right. This image shows that evaporation occurs along specific portions of the comet. Data taken by a suite of spacecraft suggests that the comet is mostly made of ice.

Halley's comet is next scheduled to return in 2062.

Last modified December 6, 2000 by Jennifer Bergman.

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