Lightning - Frequently Asked Questions

  1. What is the difference between a thundershower and a thunderstorm?
  2. What are my chances of being struck by lightning?
  3. What should I do if I'm caught out in the open during a thunderstorm and no shelter is nearby?
  4. Shouldn't I lie flat on the ground to get as low as possible?
  5. How do I avoid having to use the Lightning Crouch?
  6. Does lightning travel from the cloud to the ground, or from the ground to the cloud?
  7. If lightning travels from the ground into the cloud, why do photographs show branches of lightning descending from the cloud?
  8. How far can lightning strike?
  9. Can lightning strike me while I'm indoors?
  10. Can I use my cell phone or cordless phone during a storm?
  11. Can I be struck by lightning if I wear rubber soled shoes?
  12. I have a boat with a tall mast. How can I protect myself from lightning?
  13. I have a lightning rod on my house. Am I safe from lightning?
  14. Should I install a lightning protection system on my home or business?
What is the difference between a thundershower and a thunderstorm?
Technically, there is none. In general, the term "thundershower" tends to denote a fairly weak storm with light to moderate rainfall and low levels of lightning activity. However, there are no defined parameters that distinguish between a thundershower and a thunderstorm. In fact, in order to avoid confusion, we in the National Weather Service do not use the term "thundershower". If a shower is strong enough to produce lightning, even just one single bolt, it's called a thunderstorm. Top

What are my chances of being struck by lightning?
This is a seemingly simple question, but there is no single answer that fits everyone. The odds of being struck vary from person to person because they depend on several factors. The most significant are:

  1. Geographical location and climatology
  2. Diurnal and annual climatology
  3. Personal lifestyle/hobbies

Where there is a lot of lightning, there is an increased chance of being struck. The central Florida peninsula from Tampa Bay to Cape Canaveral has the highest lightning concentration in the United States. More than 90% of the lightning in this area occurs between May and October, between the hours of noon and midnight.

During this time of day and year, people in Central Florida who spend a large portion of their lives outdoors (e.g. construction workers, park rangers, golfers, campers etc.) are more likely to be struck than anywhere else in the country. On the other hand, thunderstorms are uncommon in the Pacific northwest, and are virtually unheard of during the winter months. People in this region who spend much of their lives indoors (e.g. shopkeepers, librarians, bowlers, billiard players, etc.) might win the lottery before they were struck by lightning. It is impossible to assign one single probability to every person in every situation.

The general odds from the National Weather Service Lightning Safety site (http://www.lightningsafety.noaa.gov/medical.htm)...

Odds of Becoming a Lightning Victim
U.S. 2000 Census population as of 2008 300,000,000
Number of deaths actually reported: 60 Number of injuries reported: 340 (total) 400
Estimated number of actual U.S. deaths: 60 Estimated number of actual injuries: 540 (total) 600
Odds of being struck by lightning in a given year (reported deaths + injuries) 1/750,000
Odds of being struck by lightning in a given year (estimated total deaths + injuries) 1/500,000
Odds of being struck in your lifetime (Est. 80 years) 1/6250
Odds you will be affected by someone being struck (Ten people affected for every one struck) 1/625
Top

What should I do if I'm caught out in the open during a thunderstorm and no shelter is nearby?
There are NO SAFE PLACES outdoors during a lightning storm. Don't kid yourself--you are NOT safe outside. Following these tips will not prevent you from being struck by lightning, but may slightly lessen the odds.

If camping, hiking, etc., far from a safe vehicle or building, avoid open fields, the top of a hill or a ridge top. Keep your site 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 camping in an open area, set up camp in a valley, ravine or other low area. Remember, a tent offers NO protection from lighting. If you are camping and your vehicle is nearby, run to it before the storm arrives.

Stay away from water, wet items such as ropes and metal objects, such as fences and poles. Water and metal are excellent conductors of electricity. The current from a lightning flash will easily travel for long distances. Top

Shouldn't I lie flat on the ground to get as low as possible?
NO! Lying flat on the ground was once thought to be the best course of action, but this advice is now decades out of date. When lightning strikes the earth, it induces currents in the ground that can be fatal up to 100 feet away. These currents fan out from the strike center in a tendril pattern, so in order to minimize your chance of being struck, you have to minimize BOTH your height AND your body's contact with the earth's surface. Top

How do I avoid having to use the Lightning Crouch?
Be aware of your situation and PLAN AHEAD. If you going to be involved in an outdoor activity, make sure you know what the forecast is, ESPECIALLY if you live in a lightning prone area. If storms are forecast, have a plan of action that you can enact quickly to reduce your chances of being struck. Top

Does lightning travel from the cloud to the ground, or from the ground to the cloud?
An entire lightning strike employs both upward and downward moving forces. However, the return stroke of a lightning bolt travels FROM THE GROUND INTO THE CLOUD and accounts for more that 99% of the luminosity of a lightning strike. What we SEE as lightning does indeed travel from the ground into the cloud. Top

If lightning travels from the ground into the cloud, why do photographs show branches of lightning descending from the cloud?
In photographs, it may APPEAR that lightning is descending from the cloud to the ground, but in reality, the return stroke is so brilliant that as it travels up the strike channel, it illuminates all of the branches of the stepped leader that did not connect with a streamer. Top

How far can lightning strike?
Almost all lightning will occur within 10 miles of its parent thunderstorm, but it CAN strike much farther than that. Lightning detection equipment has confirmed bolts striking almost 50 miles away, but these are very rare. Top

Can lightning strike me while I'm indoors?
YES! If a bolt strikes your house or a nearby power line, it CAN travel into your house through the plumbing or the electric wiring! If you are using any electrical appliances or plumbing fixtures (INCLUDING telephones and computers), and a storm is overhead, you are putting yourself at risk! FACT: About 4-5% of people struck by lightning are struck while talking on a corded telephone. Top

Can I use my cell phone or cordless phone during a storm?
Yes. These are safe to use because there is no direct path between you and the lightning. Avoid using a corded telephone unless it's an emergency. Top

Can I be struck by lightning if I wear rubber soled shoes?
Absolutely! While rubber is an electric insulator, it's only effective to a certain point. The average lightning bolt carries about 30,000 amps of charge, has 100 million volts of electric potential, and is about 50,000°F. These amounts are several orders of magnitude HIGHER than what humans use on a daily basis and can burn through ANY insulator (even the ceramic insulators on power lines!) Besides, the lightning bolt may just have traveled many miles through the atmosphere, which is a good insulator. Your ½" (or less) of rubber will make no difference. Top

I have a boat with a tall mast. How can I protect myself from lightning?
Install a lightning protection system and make sure your insurance covers lightning damage. Lightning tends to strike the tallest object and boats on the open water fit this profile to a tee. Lightning protection systems WILL NOT prevent your boat from being struck, but they can help minimize the damage. Top

I have a lightning rod on my house. Am I safe from lightning?
Lightning rods will not prevent your building from being struck. They actually INCREASE it by making your house TALLER. The purpose of the lightning rod is to direct the current from the lightning to the ground along a preferred path instead of to the house. However, this works only if the rod is connected to the ground with heavy gauge wire.Top

Should I install a lightning protection system on my home or business?
It depends. Do you have electrically sensitive equipment and do you think your building may be struck? Contrary to some popular beliefs, lightning protection systems DO NOT prevent lightning. Instead, they actually bank on the assumption that your building will be struck. They help mitigate damage by giving the lightning a preferred pathway into the ground, not unlike a flood spillway system. Top

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