Lightning kills more people in the United States in a year than tornadoes. Lightning results from the buildup and discharge of electrical energy between positively and negatively charged areas. Rising and descending air within a thunderstorm separates these positive and negative charges. Water and ice particles also affect charge distribution. A cloud-to-ground lightning strike begins as an invisible channel of electrically charged air moving from the cloud toward the ground. When one channel nears an object on the ground, a powerful surge of electricity from the ground moves upward to the clouds and produces the visible lightning strike.
Lightning Facts• Lightning causes an average of 80 fatalities and 300 injuries each year.
• Lightning occurs in all thunderstorms, each year lightning strikes the Earth 20 million times.
• The energy from one lightning flash could light a 100-watt light bulb for more than 3 months.
• Most lightning fatalities and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
• Lightning can occur from cloud-to-cloud, within a cloud, cloud-to-ground, or cloud-to-air.
• Many fires in the western United States and Alaska are started by lightning.
• The air near a lightning strike is heated to 50,000°F which is hotter than the surface of the sun. The rapid heating and cooling of the air near the lightning channel causes a shock wave that results in thunder.
30/30 Lightning Safety RuleThe first "30" represents 30 seconds. If the time between when you see the flash and hear the thunder is 30 seconds or less, the lightning is close enough to hit you. If you haven't already, seek shelter immediately. The second "30" stands for 30 minutes. After the last flash of lightning, wait 30 minutes before leaving your shelter. More than one half of lightning deaths occur after a thunderstorm has passed.
Lightning and Mariners
Mariners are particularly at risk. Marine vessels are often the tallest objects in a large open space. A direct lightning hit can damage or destroy vessels, overload navigational and other electronic systems, and electrocute crew and passengers.
St. Elmo's Fire
The glow on a masthead produced by an extreme buildup of electrical charge is known as St. Elmo's Fire. Unprotected mariners should immediately move to shelter when this phenomena occurs. Lightning may strike the mast within five minutes after it begins to glow.
Out on the Water
If a thunderstorm catches you while you are on water:• Keep away from metal objects not grounded to the vessel's protection system. Contact with them during a direct hit can cause electrocution.
• Stay out of the shower. The electrical charge often travels along and through plumbing.
• Wear a life jacket at all times. A victim struck by lightning can be rendered unconscious and fall overboard.
Lightning Myths and FactsMyth: If it is not raining, then there is no danger from lightning.
Fact: Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall. This is especially true in the western United States where thunderstorms sometimes produce very little rain.
Myth: The rubber soles of shoes or rubber tires on a car will protect you from being struck by lightning.
Fact: Rubber-soled shoes and rubber tires provide NO protection from lightning. The steel frame of a hard-topped vehicle provides increased protection if you are not touching metal. Although you may be injured if lightning strikes your car, you are much safer inside a vehicle than outside.
Myth: People struck by lightning carry an electrical charge and should not be touched.
Fact: Lightning-strike victims carry no electrical charge and should be attended to immediately. Contact your local American Red Cross chapter for information on CPR and first aid classes.
Myth: "Heat lightning" occurs after very hot summer days and poses no threat.
Fact: "Heat lightning" is a term used to describe lightning from a thunderstorm too far away for thunder to be heard.
Lightning information courtesy of the National Weather Service.