From the Archives - June 2000

Most aviators recognize the power of lightning, but few understand this unique natural phenomenon. Take time to review a few facts about lightning.

1. A typical thunderstorm lasts about 30 minutes.

2. Though most tend to occur in the afternoon and evening during the spring and summer, thunderstorms can occur at any time of the day and along frontal boundaries.

3. Lightning can strike as far as 15 miles away from a thunderstorm.

4. Lightning can occur when it is not raining.

5. Deaths caused by lightening average 93 per year. AN additional 300 people are injured by lightning as well.

6. Of all those killed or injured by lightening, 84 percent are males; 16 percent are females.

7. Most lightning incidents in the United States occur in the month of July.

8. The average lightning stroke (bolt) is discharged from cloud to ground in half a second.

9. There are roughly 5 to 10 times as many cloud-to-cloud flashes as there are cloud-to-ground flashes.

What is lightning?

Lightening, simply put, is the difference in charge between the cloud (thunder cell) and the earth below. All water molecules carry an electrical charge. As rain is carried upward in a thundercloud, it freezes and builds a positive electrical charge. Most of the rain at the base of the cloud is negatively charged.

As the frozen raindrops become too heavy to be held by the cloud, they fall and begin to warm and melt. Scientists assume that in the charged path, the lightning bolt follows these falling, melting drops. When a good connection is found on the earth's surface, the circuit is completed and the lightning bolt discharges.

Since 1989, when a national lightning detection network first recorded lightning strikes, more than 20 million cloud-to-ground flashes have been recorded each year in the continental 48 states. About half of these struck more than one point at the same time. Thus, the number of actual ground contacts is closer to 30 million per year!

Each bolt of lightning can be charged with up to 100 million volts and 50 thousand amperes (amps) of electrical power. Keep in mind that one-sixth of an amp can kill a human being!

Where does it strike most often?

Because of atmospheric conditions, the area between Tampa and Orlando in Florida has seen a greater number of cloud-to-ground strikes than any other part of the continental United States. Large amounts of moisture in the air at or below the 5,000-foot level, high surface temperature and resulting strong ocean breezes all contribute to the formation of powerful thunderclouds.

Historical records show that most lightning deaths and injuries occurred on Sunday, Wednesday and Friday between 2 p.m. and 6 p.m. The majority of these incidents (91 percent) involved one person; two or more individuals per incident made up the remaining 9 percent.

Florida, Michigan, Texas, New York and Tennessee have had the greatest number of deaths due to lightning, while Florida, Michigan, Pennsylvania, North Carolina and New York recorded the greatest number of injuries.

How damaging is lightning?

Data provided by the National Safety Institute shows that from 1940 to 1991, lightning was among the top four natural phenomena leading to human death in the United States, causing more deaths than tornadoes, hurricanes or floods.

During that period, 8,316 people died as a result of lightning. In that same period, 5,828 were killed by floods; 5,731 were killed by tornadoes; and 2,031 were killed by hurricanes.

Lightning also takes a social and economic toll. Many people who are hit by lightning never fully recover from the incident. Many bear permanent injuries and scars. Some suffer major psychological as well as physiological trauma and aftereffects.

Lightning damages or destroys homes and personal property. For example, from 1990 to 1992 lightning caused over $27 million in personal property damage annually across the nation. Another source shows lightning-related expenses averaged $138.7 million from 1989 to 1993.

Commercial losses to building, hangars, aircraft and other aviation equipment can quickly total in the hundreds of millions of dollars across the country in a year.

Recently we have seen a rise in the number of super storms (storms with greater than average intensity). Some scientists believe that this is a result of El Niño or La Niña, while others think it is a result of global warming. Whatever the case, without adequate steps to prevent or greatly reduce lightning damage, the dollar figures surely will continue to rise.

What can I do to be safe?

Above all, if you are outside, do not stand under a tree or next to a telephone pole! Turn off your cell phone and put it away. Never lean against metal fences or signposts. Don't touch metal pipes or stand on or near metal floor/ground grates.

If you are on top of a hill, go to the lower part of the hill. In open areas, find a ravine or valley, but also be mindful of flash flood possibilities. Stay away from open water. Do not operate tractors or other farm equipment, motorcycles, bicycles or golf carts.

Don't even touch your golf clubs and remove spiked golf shoes. Replace them with rubber sole sneaker-type shoes. If you are in a group, spread out! Make sure that you are three to five yards from the next person.

When you feel your hair standing on end, you may be about to experience a lightning hit or near-hit. Don't panic! Drop to your knees – do not lie flat down to the ground. Put your hands on your knees and bend forward, making yourself the smallest and hopefully lowest object around. Remove all jewelry.

The best thing to do is to immediately find shelter when you see a storm developing. Stay inside a substantial building and wait until the storm has passed. Do not sit in front of or near a window (keep in mind that straight-line winds from a thunderstorm can sometimes exceed 100 miles per hour). While inside, avoid using the telephone or any electrical appliances. Avoid metal sinks and bathtubs.

In general, just use good common sense and judgement, and you can avoid becoming a flash statistic for the next report!