Dr. Lightning’s Guide To National Weather Service Lightning and Thunder -- An Introduction -- National Weather Service NOAA

Written, illustrated, and animated An Introduction To Lightning and Thunder Written, illustrated, and animated by John Jensenius aka: Dr. Lightning

Lightning Across The United States Each Flash Is A Potential KILLER ! That’s a lot of potentially deadly bullets from the sky!

Lightning Across The United States This map shows the average number of lightning strikes across the United States. Although Florida, the Gulf Coast, and the central U.S. see the most lightning, lightning can occur anywhere.

A Threat In All Seasons Lightning can strike in any season. Lightning occurs most often during summertime thunder- storms. However, lightning can occur in intense winter storms, too. Whether it’s summer or winter, if you hear thunder, the storm is close enough to strike, and you need to get inside a safe place immediately.

What Is Lightning ? Lightning is a giant spark of electricity within the cloud or between the cloud and the ground.

Lightning and Trees For most of the country, if you go outside, the tallest thing around you is usually a tree. Because lightning tends to strike tall objects, trees are often struck by lightning. This is why standing under or near a tree is so dangerous. You don’t want to stand out in the open either since that would make you the tallest object in the area. The only safe solution is to get inside a substantial building or hard-topped vehicle as soon as you see lightning or hear thunder.

We Can’t Predict Exactly Where Lightning Will Strike While lightning often strikes the tallest object around, sometimes the lightning doesn’t realize a tall object exists and strikes the ground nearby. In this picture, lightning struck the base of the space shuttle despite efforts by scientists to prevent this from happening. The white pointed pole was designed to intercept any lightning and provide a path to the ground but, in this case, it didn’t work!

Lightning and Cars Cars and other vehicles are struck by lightning every year. The lightning may melt an antenna, shatter a window, damage the electronics, and blow out the tires. But, fortunately, the outer metal shell of the vehicle protects the people inside.

Lightning and Planes Planes are frequently struck by lightning. On average, each commercial passenger plane is struck by lightning once or twice a year. Commercial planes are designed to withstand lightning strikes and to conduct the electrical currents safely around the shell of the plane.

Lightning and Fish Bodies of water are also often struck by lightning. So why don’t all the fish die? Before a lightning strike, there is a charge build up along the water’s surface. When lightning strikes, most of electrical discharge occurs near the water’s surface. Most fish swim below the surface and are unaffected.

How Powerful Is Lightning? A typical lightning flash is 300 million Volts and 30,000 Amps. In comparison, household current is about 120 Volts and 15 Amps.

How Powerful Is Lightning? There is enough energy in a typical flash of lightning to light a 100-watt incandescent light bulb for about three months or the equivalent compact fluorescent bulb for about a year.

How Hot Is Lightning ? Lightning heats everything it is passing through. If an object is a good conductor of electricity, it won’t heat up as much as a poor conductor. Air is a very poor conductor of electricity and gets extremely hot when lightning passes through it. In fact, lightning can heat the air it passes through to 50,000 degrees Fahrenheit (5 times hotter than the surface of the sun).

Lightning and Fires Lightning causes about 25,000 fires each year including more than 4000 house fires. If your house is struck by lightning and you see fire or smell smoke, evacuate your house immediately and call 911. Also call your local fire department and, if possible, have them check for hot spots in the walls with thermal imaging equipment.

Thunder Thunder is the sound caused by a nearby lightning flash. When lightning passes through the air, it heats the air very rapidly and causes it to expand. Immediately after the flash, the air cools and contracts quickly. This rapid expansion and contraction creates the sound wave that we hear as thunder.

Thunder While you see lightning immediately, the sound of thunder travels outward from the lightning flash at about 1100 feet per second. That’s about a mile every five seconds. The farther you are from the lightning flash, the longer it will take for the sound of thunder to reach you.

How Do I Tell How Far Away The Lightning Is? If you count the number of seconds between the flash of lightning and the sound of thunder, and then divide by 5, you’ll get the distance in miles to the lightning. 30 seconds = 6 miles 15 seconds = 3 miles 5 seconds = 1 mile 0 seconds = very close Be sure you are in a safe place while counting! If you can hear thunder, chances are that you’re within striking distance of the storm. On the next page, you can test your knowledge. Watch for the flash of lightning, then begin counting. See if you can calculate the distance before it appears on the screen.

How Far Away Is The Lightning ? TIMER 1 10 9 8 5 6 7 2 4 3 10 / 5 = 2 miles

“Heat Lightning” Normally, you can hear thunder if you’re less than 10 miles from a lightning strike. For storms more than 10 miles away, although you may see flashes of light, you’re probably too far away to hear the thunder. Many people call this “heat lightning,” but, in reality, it’s just normal lightning from a distant thunderstorm. In many cases, the light you see is being reflected off high clouds near the storm.

Lightning Safety There are a few simple guidelines that can keep you safe from lightning. Lightning can strike 10 miles from a thunderstorm which is about the distance that you can hear thunder. If you hear thunder, you’re likely within striking distance of the storm. If you hear thunder, even a distant rumble, get to a safe place immediately. Remain in that safe place for 30 minutes after the last lightning or thunder. Proper planning may be needed for many summertime activities so that you can get to a safe place quickly. You don’t want to get caught outside in a thunderstorm and not have a safe place to go.

Lightning Safety A house, school, or large building provides good protection from lightning. Just don’t touch anything that is plugged into a wall outlet; stay off corded phones; avoid contact with the plumbing, including sinks and tubs; and stay away from windows and doors.

Lightning Safety A car, bus, or van with a metal roof also provides good protection from lightning. Roll up the windows and keep your arms, hands, and legs inside the vehicle.

“When Thunder Roars, Go Indoors” Lightning Safety “When Thunder Roars, Go Indoors” Leon, the Lightning Safety Lion, has a simple saying that will help keep you safe.

For More Information Visit Our Web Site www.lightningsafety.noaa.gov

NOAA Wants You To Have A Safe And Enjoyable Summer If you have any comments or suggestions, please email: Dr.Lightning@noaa.gov