Flash Facts About Lightning

National Geographic News
Updated June 24, 2005

Organized by the National Oceanic and Atmospheric Administration (NOAA) and other partners, Lightning Safety Week is held the last full week of June each year.

Lightning is one of the leading weather-related causes of death and injury in the United States. Most people do not realize that they can be struck by lightning even when the center of a thunderstorm is 10 miles (16 kilometers) away and there are blue skies overhead.

Did you know that rubber shoes do nothing to protect you from lightning? That talking on the telephone is the leading cause of lightning injuries inside the home? That standing under a tall tree is one of the most dangerous places to take shelter?

And what does it mean if your hair starts to stand on end during a thunderstorm?

Scroll down for the answers to these and other questions—and for tips and procedures to protect yourself and your property against one of nature's most lethal phenomena.

• Lightning is a giant discharge of electricity accompanied by a brilliant flash of light and a loud crack of thunder. The spark can reach over five miles (eight kilometers) in length, raise the temperature of the air by as much as 50,000 degrees Fahrenheit (27,700 degrees Celsius), and contain a hundred million electrical volts.

• Some scientists think that lightning may have played a part in the evolution of living organisms. The immense heat and other energy given off during a stroke has been found to convert elements into compounds that are found in organisms.

• Lightning detection systems in the United States monitor an average of 25 million strokes of lightning from clouds to ground during some 100,000 thunderstorms every year. It is estimated that Earth as a whole is struck by an average of more than a hundred lightning bolts every second.

The odds of becoming a lightning victim in the U.S. in any one year is 1 in 700,000. The odds of being struck in your lifetime is 1 in 3,000.

Lightning can kill people (3,696 deaths were recorded in the U.S. between 1959 and 2003) or cause cardiac arrest. Injuries range from severe burns and permanent brain damage to memory loss and personality change. About 10 percent of lightning-stroke victims are killed, and 70 percent suffer serious long-term effects. About 400 people survive lightning strokes in the U.S. each year.

• Lightning is not confined to thunderstorms. It's been seen in volcanic eruptions, extremely intense forest fires, surface nuclear detonations, heavy snowstorms, and in large hurricanes.

• Ice in a cloud may be key in the development of lightning. Ice particles collide as they swirl around in a storm, causing a separation of electrical charges. Positively charged ice crystals rise to the top of the thunderstorm, and negatively charged ice particles and hailstones drop to the lower parts of the storm. Enormous charge differences develop.

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