Watching a summer lightning and thunder storm is an awesome experience, but it can be frightening.
An estimated 2,000 thunderstorms occur worldwide at any moment. Lightning strikes the earth more than 100 times per second. While lightning strikes humans in only a fraction of these storms, about 150 to 300 people annually are killed by lightning in the United States. Lightning claims more lives in the United States than any other natural disaster, including earthquakes, blizzards, tornadoes, floods, hurricanes and volcanic eruptions.In the past, farmers, sailors and others who worked outdoors in isolated areas tended to be the most frequently injured. Today, a larger proportion of victims are hikers, campers, golfers, and others who are outdoors for recreational purposes.
Almost 70 percent of lightning deaths involve just one person. Fifteen percent of victims are killed in groups of two, and another 15 percent are fatally injured in groups of three or more. Lightning deaths happen more often during daytime hours when people are active and outdoors. Most occur in the summer months of June through September when thunderstorms are most frequent. There are more thunderstorm days in the South than in any other region.
Thunderstorms occur frequently over high mountains. People are better protected in urban areas where high buildings have metal frames and lightning devices.
Myths about lightning
Some myths about lightning include:
1. Lightning strikes are always fatal. Actually, studies report that lightning strikes kill only 20 percent to 30 percent of those struck. Generally, only those who sustain immediate cardiac arrest die. Those who are stunned or lose consciousness without cardiac arrest are highly unlikely to die.
2. A lightning-struck victim retains the charge and is dangerous to touch, since he/she is still "electrified." This false idea has led to a delay of resuscitation efforts and probably to some unnecessary deaths.
3. Lightning strike injuries allow a long resuscitation effort. This belief was erroneously based on the idea of "suspended animation" that allowed a longer period in which to resuscitate the victim. While rescue breathing (with a pulse) can effectively sustain life for long time periods, CPR (cardiopulmonary resuscitation) is usually ineffective after 30 minutes for a cardiac arrested victim.
4. Lightning never strikes twice in the same place. Nothing could be further from the truth. The Sears Tower and the Empire State Building get hit thousands of times a year, as do mountain tops and radio-television antennas.
5. A person inside a building is safe from lightning injury. Electrical current traveling along plumbing fixtures, telephone wires and other appliances attached to the outside of the house by metal conductors have been reported. Telephone companies publicize warnings against using telephones during thunderstorms.
Distance from lightning
The thunderclap from a lightning bolt is heard as a sharp crack. Distant thunder rumbles as the sound waves are modified. The difference in speeds between light and sound gives an estimate of the distance to the lightning strike. If one takes the differences in seconds between seeing the flash and hearing the rumble and divide by 5, the approximate distance to the flash in miles is obtained.
How lightning injures
1. Direct strike. This is actually being struck by lightning. A direct strike is most likely to hit a person in the open who has been unable to find shelter. Any conductor that the victim carries, especially if it is metal and carried above the shoulder level (i.e., umbrella, golf clubs, etc.) increases the chances of a direct hit.
2. Splash. A more frequent cause of injury is that from a splash. This happens when lightning that has hit a tree or building splashes onto a victim who may be seeking shelter nearby. The electrical current, seeking the path of least resistance, may jump to a person whose body has less resistance than the tree or object that the lightning has initially contacted. Frequently, groups of animals have been killed as they stood near a fence or sought shelter under trees.
3. Contact. Contact injury happens when the person is holding onto an object that is either directly hit or splashed by lightning.
4. Ground current. Ground current is produced when lightning hits the ground or an object nearby. The current spreads like a wave in a pond. Although ground current is less likely to produce fatalities than are direct hits or splashes, it often creates multiple victims and injuries. Large groups have been injured on baseball fields, hiking or on military maneuvers.
5. Blast effect. People may be injured by the explosive force of the shock wave produced as lightning hits nearby. The victim is actually thrown.
Differences between injuries from high voltage electricity and lightning:
Lightning contact with the body is almost instantaneous, leading to flashover. Since the current flashes over the body instead of going through it, there are seldom burns of any magnitude. Exposure to high-voltage electricity tends to be much more prolonged, as the victim freezes to the circuit. The electrical energy surges through the tissues with little resistance to flow, causing massive internal thermal injury, with major amputations resulting.