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Lightning Week
Mon Jun 20, 2005
Listen in RealAudio 
Today marks the beginning of the 4th annual Lightning Safety Awareness Week, and so we will devote this week to shows all about lightning. And keeping you safe from it. Hi, I’m Bryan Yeaton, and this is The Weather Notebook.
For the past 40 years, lightning has killed more people in the United States than any other storm-related happening, save floods. Sixty-seven people are reportedly killed every year in this country, but the real number is probably closer to 100, according to the National Weather Service Publication “Storm Data.” And yet, only a tenth of folks who are struck are killed, leaving many of the others with sometimes permanent consequences.
If you live to be 80 years old, the chance of being struck in your lifetime is one in three thousand. In any given year, those odds are one in 700,000.
Scientists are coming to understand the role that ice plays in lightning formation. Although lightning producing storms most often occur in the hottest months, the upper regions of the storm are still extremely cold, since their tops are 6-10 miles above the surface. Collisions between tiny ice crystals separate electrical charges; much of the positive charge collects in the top of the cloud, and with the negative concentrated at the cloud’s base. Since like charges repel, the negative in the bottom of the cloud pushes away negative charge underneath it on the surface, leaving what is called a “positive shadow.” When the differential between these is big enough, a big spark arcs through the air—normally a wonderful insulator—to the ground. Flash and boom! You’ve got your thunder and lightning.
For more on Lightning Safety Week, charge over to our website for a link. The Weather Notebook is a program of the Mount Washington Observatory, funded by Subaru of America. Find us online at www.weathernotebook.org.
Today's Links
http://www.lightningsafety.noaa.gov/week.htm
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