When Lightning Strikes

Lightning Position
This illustration shows the position you should assume in the event of a lightning strike.

I had another sleepless night. My poor dog is terrified of thunder, and the sky was alive with lightning and thunder once again. It seems as if this summer has had a very active thunderstorm season, and the news is frequently reporting lightning strikes.

Typically, there are about 50 deaths and 400 injuries a year in the United States caused by lightning. Lightning also is responsible for many house fires as we saw the other week on James Island. Wildfires also commonly are started by lightning.

Lightning develops when warm air mixes with cold air masses. It is more frequent in the warmer area of our country, such as the Southeast. It also can be seen in dust storms, forest fires, tornadoes, volcanic eruptions and during a cold winter.

Lightning is an electrical charge similar to static electricity. The thundercloud becomes charged when the small frozen raindrops bump around each other, such as when we walk on carpet with rubber sole shoes. There are positive charges in the top of the cloud and negative charges in the bottom. Positive charges also develop around objects on Earth, especially taller objects like buildings, trees or even you.

As we know, opposite charges attract, and the negative charges from the clouds connect with the positive charges on the ground to produce lightning. This is similar to touching a door knob and feeling the shock. A lightning strike produces around 30,000 amps of energy. Household currents are 15 amps for comparison. The strike is six times hotter than the sun, so you can understand why it frequently causes fires.

Thunder is a sound wave that develops after the lightning strike. The lightning produces a hole or channel in the air, and the thunder is developed as the air collapses back into the hole. Sound travels slower than light. You can see lightning up to 100 miles away but hear thunder only five to 15 miles away. You can estimate the distance the storm is from you by counting the seconds between seeing the lightning and hearing the thunder and dividing by five. For example, if you count 10 seconds between lightning and thunder, the lightning is two miles away (10/5= two miles away).

Most lightning strikes occur under the thundercloud, but 5 percent of strikes can occur miles away from the storm, even under a cloudless sky. This is where the saying “out of the blue” came from.

As a good rule of thumb, if you hear thunder, you should seek shelter immediately. The safest shelter is a structure with four walls, roof, plumbing and electricity in short, a house. It is best to avoid a pavilion, dugout or concrete-floored structure.

The next best place to seek shelter is a car with the windows rolled up. When you are in a building, be sure to avoid using electronics, showering or washing your hands. Lightning can enter the structure through the electronics or water pipes. In the car, avoid using electronics or coming in contact with metal surfaces.

If you are caught outside, you want to avoid trees and get to the lowest place available. Assume the lightning position, which is crouching down with your feet close together. Bend over and hug your knees and bow your head. Also, close your eyes. It is better if you are wearing rubber sole shoes or standing on a foam mat. Wet ground is not more dangerous than dry but avoid standing water. Definitely get out of the swimming pool or river.  If you are in a group, separate as much as you can.

Remember if you feel the hair on your head or arms stand up, a lightning strike is imminent so you need to react immediately. Metal fences and wet ropes are great conductors of lightning, so they should be avoided. Backpacks also should be removed because they have metal components. You can protect your home electronics by unplugging them during a storm. Lightning can overwhelm surge protectors and destroy your computer or TV. You also should be sure that your home is grounded. I recently discovered that my older home was not grounded and had to retrofit it.

If you are on the water when the storm develops, get to shore as quickly as possible. Once on shore, avoid the trees at the water’s edge since they attract the lightning. If you can’t get to shore, go in the cabin if there is one and avoid all electronics. I have spent many a storm on a sailboat offshore thinking how we were truly the tallest structure for miles around. There are lightning protection systems for larger boats that are important to install. If you are in a boat without a cabin, assume lightning position as low in the boat as possible. And once again, avoid using electronics during the storm.

In the event of a lightning strike, the common injuries include electric shock, which causes the heart and breathing to stop. The heart usually starts back after the strike, but the breathing needs to be supported. The individual is not charged so you will not get hurt if you assist them.

Strikes also can cause significant burns either directly from the lightning or indirectly from metal on clothing, such asa belt buckle. The force of the strike can be so strong that the victim can sustain fractures of bones or soft tissue injury. Foot fractures are common in this situation. There possibly can be neurologic injuries, including amnesia and altered consciousness.

Fortunately, there are relatively few people who are hit by lightning every year. You can protect yourself by checking the weather forecast before going on an outdoor adventure. If there is a high probability of a thunderstorm, change your plans. If you hear thunder, seek shelter immediately and stay indoors until there has been no thunder for 30 minutes. In the unlikely event of someone being struck by lightning, call 911 and start CPR if needed.

By following these simple rules, you will remain safe during this very active thunderstorm season.

By: Dr. Valerie Scott, board certified family medicine doctor. She practices at Mt. Pleasant Family Practice.