Lightning: What You Need to Know
- NO PLACE outside is safe when thunderstorms are in the area!!
- If you hear thunder, lightning is close enough to strike you.
- When you hear thunder, immediately move to safe shelter: a substantial building with electricity or plumbing or an enclosed, metal-topped vehicle with windows up.
- Stay in safe shelter at least 30 minutes after you hear the last sound of thunder.
What is a safe location?
Substantial buildings with wiring and plumbing are the safest places. Office buildings, schools, and homes offer good protection. Once inside, stay away from windows and doors and anything that conducts electricity such as corded phones, wiring, plumbing, and anything connected to these.
What is Lightning?
Lightning is a giant spark of electricity in the atmosphere or between the atmosphere and the ground. In the initial stages of development, air acts as an insulator between the positive and negative charges in the cloud and between the cloud and the ground; however, when the differences in charges becomes too great, this insulating capacity of the air breaks down and there is a rapid discharge of electricity that we know as lightning.
Understanding Lightning: Thunder
Thunder is the sound caused by a nearby flash of lightning and can be heard for a distance of only about 10 miles from the lightning strike. The sound of thunder should serve as a warning to anyone outside that they are within striking distance of the storm and need to get to a safe place immediately!
Thunder is created when lightning passes through the air. The lightning discharge heats the air rapidly and causes it to expand. The temperature of the air in the lightning channel may reach as high as 50,000 degrees Fahrenheit, 5 times hotter than the surface of the sun. Immediately after the flash, the air cools and contracts quickly. This rapid expansion and contraction creates the sound wave that we hear as thunder
How Far Away Was That Lightning?
The sound of thunder travels about a mile every 5 seconds. If you count the seconds between the flash of lightning and the crack of thunder and divided by 5, you get the number of miles away from you (10 seconds is 2 miles).
Indoor Lightning Safety
- Stay off corded phones (you can use cellular or cordless phones), computers and other electrical equipment that put you in direct contact with electricity.
- Avoid plumbing, including sinks, baths and faucets. Do Not wash hands, dishes or take shower.
- Stay away from windows and doors, and stay off porches.
- Do not lie on concrete floors, and do not lean against concrete walls.
Last Resort Outdoor Risk Reduction Tips
If you are caught outside with no safe shelter anywhere nearby the following actions may reduce your risk:
- Immediately get off elevated areas such as hills, mountain ridges or peaks
- Never lie flat on the ground
- Never shelter under an isolated tree
- Never use a cliff or rocky overhang for shelter
- Immediately get out and away from ponds, lakes and other bodies of water
- Stay away from objects that conduct electricity (barbed wire fences, power lines, windmills, etc.)
When a Safe Location is not Nearby
If you absolutely cannot get to safety, you can slightly lessen the threat of being struck with the following tips. But don't kid yourself--you are NOT safe outside. Know the weather patterns of the area you plan to visit. For example, in mountainous areas, thunderstorms typically develop in the early afternoon, so plan to hike early in the day and be down the mountain by noon. Listen to the weather forecast for the outdoor area you plan to visit. The forecast may be very different from the one near your home. If there is a high chance of thunderstorms, stay inside.
- Avoid open fields, the top of a hill or a ridge top.
- Stay away from tall, isolated trees or other tall objects. If you are in a forest, stay near a lower stand of trees.
- If you are in a group, spread out to avoid the current traveling between group members.
- If you are camping in an open area, set up camp in a valley, ravine or other low area. Remember, a tent offers NO protection from lighting.
- Stay away from water, wet items, such as ropes, and metal objects, such as fences and poles. Water and metal do not attract lightning but they are excellent conductors of electricity. The current from a lightning flash will easily travel for long distances.