Thunderstorm Information

What is a thunderstorm?

A thunderstorm is a type of storm with lightning and thunder. They are caused by an updraft, which occurs when warm, moist air rises vertically into the atmosphere. The updraft creates a cumulus cloud, which will eventually be the thunderstorm cloud.

The basic ingredients that form a thunderstorm are:

• Moisture - torn form clouds and rain
• Unstable air - warm air that can raise rapidly
• Lifting mechanism - caused by cold or warm fronts, sea breezes, mountains, or heat from the sun

What causes a thunderstorm?

Thunderstorms are a way for the atmosphere to release energy. When warm moist air meets cold dry air, the warm air rises; the water vapor condenses in the air, and forms a cloud. As the water vapor condenses, it releases heat, which is a form of energy. A large amount of the thunderstorm's energy comes from the condensation process that forms the thunderstorm clouds. As the thunderstorm progresses, eventually the rain cools the entire process down and the energy is gone.

Why do thunderstorms occur in nature?

Thunderstorms help keep the Earth in electrical balance. The Earth's surface and the atmosphere conduct electricity easily as the Earth is charged negatively and the atmosphere, positively.

What are the hazards associated with thunderstorms?

Thunderstorms are dangerous and can be associated with a number of hazards.

• Heavy rains can lead to flood. Flood waters can plow through earthen dams, pull homes off their foundations and sweep them away, knock out power lines, and contaminate drinking water for weeks.
• Lightning can set off building or farm fires, damage electrical equipment, and electrocute humans and livestock.
• High winds can cause damage to homes, overturn vehicles, uproot or damage trees, or blow down utility poles causing wide spread power outages.
• Hail damages roofs, shatters windows, smashes vehicles and aircraft, kills animals, and injures –even sometimes kills- people.

What is lightning?

Lightning is a form of electricity in the atmosphere. During the first millionth of a second in a common lightning strike, a negative charge probes downward from the cloud. At the same time, a positive charge probes skyward. When they connect, up to one billion watts of electricity blasts upwards. The air in the lightning bolt turns into plasma, as hot as 50,000°F, ten times hotter than the surface of the sun.

What damage can lightning do?

Lightning strikes can set trees or houses on fire. Lightning can enter your home by following wires and pipes that go into the ground; it can also travel through metal reinforcing wire or bars in concrete and explode. Lightning often knocks out power lines and sends powerful electrical surges through electrical and phone lines. Once in your home, they can burn out appliances and other electronics.

Lightning Myths and Facts

	Myth	Fact
	If you are caught outside during a thunderstorm, you should crouch down to reduce your risk of being struck.	Crouching does not make you any safer outdoors. Run to a substantial building or hard topped vehicle. You are NOT safe anywhere outdoors.
	Rubber tires on a car protect you from lightning by insulating you from the ground.	Most cars are safe from lightning, but it is the metal roof and metal sides that protect you. Remember, convertibles, motorcycles, bicycles, open-shelled outdoor recreational vehicles and cars with fiberglass shells offer no protection from lightning.
	If outside in a thunderstorm, you should seek shelter under a tree to stay dry.	Being underneath a tree is the second leading cause of lightning casualties.
	Structures with metal, or metal on the body like jewelry, cell phones, Mp3 players, watches, etc., attract lightning.	Height, pointy shape, and isolation are the dominant factors controlling where a lightning bolt will strike. The presence of metal makes absolutely no difference on where lightning strikes. When lightning threatens, take proper protective action immediately by seeking a safe shelter. While metal does not attract lightning, it does conduct it so stay away from metal fences, railing, bleachers, etc.
	If trapped outside and lightning is about to strike, you should lie flat on the ground.	Lying flat increases your chances of being affected by potentially deadly ground current. If you are caught outside in a thunderstorm, keep moving toward a safe shelter.
	If you touch a lightning victim, you will be electrocuted.	The human body does not store electricity. It is perfectly safe to touch a lightning victim to give them first aid.
	If you are in a house, you are 100% safe from lightning.	A house is a safe place to be during a thunderstorm as long as you avoid anything that conducts electricity such as corded phones, electrical appliances, wires, TV cables, computers, plumbing, metal doors and windows.

What is thunder?

Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a hole in the air, called a channel. Once then light is gone the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is that light travels faster than sound.

How does thunder show how far away a storm is?

Where do thunderstorms happen most often?

The image below shows how long hurricane season lasts around the U.S.

Thunderstorms can occur almost anywhere and are the beginnings of some other dangerous storms like hurricanes and tornadoes.

What are the risks of thunderstorms?

How to stay safe indoors during a thunderstorm:

During an electrical storm, avoid:

• Avoid using a land line phone. Land line-base lightning strikes are the leading cause of indoor lightning injuries in the United States.
• Avoid having any contact with appliances connected to your plumbing, because it is typically tied to your home's electrical service for grounding.
• Avoid all contact with you home's plumbing, including the shower, bath, and sinks during an electrical storm.
• Avoid all windows and doors or standing outside on porches.

How to stay safe outside in a thunderstorm:

• Find shelter immediately in a substantial and enclosed building or a metal-topped vehicle, convertibles do not provide protection.
• If you can hear thunder, you are close enough to be struck.
• Get away from isolated trees.
• Climb down and away from hilltops and other elevated areas.
• Stay away from objects and things that conduct electricity such as metal fences, power lines, or phone poles.
• Never lie flat in a field. You can still be hit through a ground-current strike.

Sources

"Flash Facts about Lightning." National Geographic News, National Geographic Society, news.nationalgeographic.com/news/2004/06/0623_040623_lightningfacts_2.html.

"Ingredients for a Thunderstorm." National Weather Service, National Oceanic and Atmospheric Administration, www.srh.noaa.gov/jetstream/tstorms/ingredient.html.

"Introduction to Thunderstorms." National Weather Service, National Oceanic and Atmospheric Administration, www.srh.noaa.gov/jetstream/tstorms/tstorms_intro.html.

"Lightning Safety Myths and Facts." National Weather Service, National Oceanic and Atmospheric Administration, www.lightningsafety.noaa.gov/myths.shtml.

"Thunderstorm Basics." NSSL The National Severe Storms Laboratory, NOAA National Severe Storms Laboratory, www.nssl.noaa.gov/education/svrwx101/thunderstorms/.