Slide 1

National Weather ServiceNOAA-- An Introduction --Dr. Lightnings Guide To Lightning and ThunderAn Introduction ToLightning and Thunder

Written, illustrated, and animated by John Jenseniusaka: Dr. Lightning

Lightning Across The United States

Each Flash Is A PotentialKILLER !Thats 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 its 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. 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 dont 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.Lightning and Trees

While lightning often strikes the tallest object around, sometimes the lightning doesnt 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 didnt work!We Cant Predict Exactly Where Lightning Will Strike

Lightning and CarsCars 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 PlanesPlanes 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 FishBodies of water are also often struck by lightning. So why dont all the fish die? Before a lightning strike, there is a charge build up along the waters surface. When lightning strikes, most of electrical discharge occurs near the waters 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 wont 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.ThunderThunder 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.

ThunderWhile you see lightning immediately, the sound of thunder travels outward from the lightning flash at about 1100 feet per second. Thats 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, youll get the distance in miles to the lightning. 30 seconds = 6 miles 15 seconds = 3 miles 5 seconds = 1 mile 0 seconds = very closeBe sure you are in a safe place while counting! If you can hear thunder, chances are that youre 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 ?123475689100TIMER10 / 5 = 2 miles

Heat Lightning

Normally, you can hear thunder if youre less than 10 miles from a lightning strike. For storms more than 10 miles away, although you may see flashes of light, youre probably too far away to hear the thunder. Many people call this heat lightning, but, in reality, its 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 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.

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, youre likely within striking distance of the storm.Proper planning may be needed for many summertime activities so that you can get to a safe place quickly. You dont 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 dont 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 IndoorsLeon, the Lightning Safety Lion, has a simple saying that will help keep you safe. Lightning SafetyFor More Information

Visit Our Web Sitewww.lightningsafety.noaa.govNOAA Wants You To

Have A Safe And Enjoyable SummerIf you have any comments or suggestions, please email:Dr.Lightning@noaa.gov