An 11-year-old girl was struck by lightning on a bright, clear day. How does that happen?

An 11-year-old girl was the victim of a lightning 

bolt on a clear, sunny day. How does that happen?  

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Discovery News - Britney Wehrle was walking with a friend on a sunny, warm day when she was suddenly struck by lightning, even though the sky above her was clear and blue.

And while that may sound like a rare or even freakish event, it's not that uncommon for lightning to travel far from its originating cloud, experts say. In some cases, bolts have struck as much as 25 miles from where they originated. Scientists refer to these wayward streaks of electricity as "bolts from the blue," since it often seems as though the lightning comes out of a clear blue sky.

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As 11-year-old Wehrle recovers from a broken arm and a burn mark on her shoulder, it may be a good time to refresh your memory about how to protect yourself from lightning. At the top of the list: Avoid exposing yourself to it.

"When thunder roars, go indoors, and stay in there for 30 minutes after you hear the last thunder clap," said Susan Buchanan, spokeswoman for the National Weather Service in Silver Spring, Md., and a member of the agency's lightning safety team.

"Lightning is unpredictable," she added. "There's no safe place outdoors in a thunderstorm. If you remain outdoors during a thunderstorm, you are taking a gamble that you won't become one of the statistics."

And those statistics are staggering.

Every year, according to the National Weather Service, the Earth experiences 16 million thunderstorms. That amounts to an average of 1,800 storms happening at any given moment. Over the course of a year, 25 million bolts strike the ground, usually during thunderstorms but also during intense forest fires, heavy snowstorms, volcanic eruptions, nuclear detonations and large hurricanes.

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Lightning kills an average of 55 people every year, Buchanan said, but it hits and severely injures hundreds more. According to calculations on NOAA's National Severe Storms Laboratory website, there is a one in 3,000 chance of getting killed or injured by lightning in your lifetime, assuming an average life span of 80 years. The chances of lightning hurting someone close to you is one in 300.

To form, lightning requires a specific combination of circumstances, said Vladimir Rakov, an electrical engineer and lightning expert at the University of Florida, Gainesville. The recipe includes hot temperatures on the ground and moist conditions, as well as strong updrafts that propel wet air into the cooler atmosphere, where it condenses and form clouds.

With its warmth, humidity and sea breezes that blow off two coasts, Florida experiences more lightning than any other state. But even there, clouds have to get high enough for ice to form, because electrification only happens within clouds that contain water in both its solid and liquid states.      More