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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 picture shows a bright Leonid meteor that was seen in November 1998. The light from this meteor lit up some clouds, creating this beautiful photo opportunity!
Click on image for full size
Courtesy of Lorenzo Lovato of Imola, Italy

Leonid Meteor Shower

The Leonid meteor shower is one of several major meteor showers that occur on roughly the same date each year. The Leonids typically "peak" (are at their greatest level of activity) in mid to late November. The Leonid shower's name is derived from the fact that its meteors appear to fan out from a point in sky, called the shower's "radiant", which lies within the constellation Leo.

In 2009, the Leonid shower is expected to peak on the night of Tuesday, November 17th. Since there will be a New Moon around this time, this year should be a good year to spot some Leonids. A bright Moon makes it hard to see meteors.

As is the case with most meteor showers, it will be possible to see Leonid meteors for several days before and after the peak on the 17th. In fact, it is sometimes possible to see some Leonids as early as November 14th and to continue to spot a few up to November 21st. At this shower's peak observers may be able to see as many as 100 "shooting stars" per hour under dark skies (away from city lights). However, the Leonids, as compared to other meteor showers, present a highly variable celestial show. The number of meteors visible at the shower's peak can change quite a bit from year to year in an unpredictable fashion.

The Leonids are actually bits of dust that have been shed over the centuries by a comet named comet 55P/Tempel-Tuttle! The dust, which spews forth from the comet's nucleus each time it passes near the Sun, gradually spreads out over the entire orbit of the comet. If Earth's orbit happens to cross the comet's orbit, the swarm of debris scattered along the comet's orbit is visible to us as a meteor shower. Since the Earth crosses the comet's orbit at the same time each year, each meteor shower is predictably visible at the same time of year, year after year.

Most meteors in a shower are quite small, about the size of a grain of sand. Leonids are among the fastest-moving meteors. These meteors typically strike our atmosphere while traveling at speeds around 72 kilometers per second (about 161,000 mph). Because of their high speeds, Leonids typically leave long, glowing trails in the sky.

Last modified October 20, 2009 by Randy Russell.

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