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The No. 1 Life Threatening Weather Hazard

Lightning From Stapleton
Tim Wieland took this photo in July 2011 from a hill in Denver's Stapleton neighborhood as heavy storms passed across the metro area.

Written by Meteorologist Dave AguileraLightning is Colorado's No. 1 life threatening weather hazard. One bolt of lightning can be 50,000 degrees Fahrenheit, that's five times as hot as the surface of the sun! The state averages 3 fatalities and 13 injuries per year from lightning.

A good motto from the National Weather Service is "WHEN THUNDER ROARS, GO INDOORS!" Lightning is nothing to mess around with. A good rule of thumb is to wait at least 30 minutes from the last rumble to go back outside.

What is thunder?

Lightning causes thunder. As a result of the tremendous heat with a lightning bolt, the air along and in the channel that lightning creates expands. This rapidly expanding air creates the sound we call thunder.

How is lightning formed?

Simply put lightning is a huge spark that occurs during a thunderstorm. The reason for this electrical discharge is the attraction of positive and negative electrons. The friction caused by the strong updrafts and downdrafts moving particles inside of a thunderstorm help to create an electrical charge. During this process positive charges (protons) build up in the top of the thunderstorm (cumulonimbus cloud). At the same time negative charges (electrons) gather at the bottom of the thunderstorm. Then, these negative charges are attracted to positive charges that are coming together on the ground. When the negative charges meet the positive charges, bingo, you have lightning. Have you ever been shocked by a tiny spark when you touch a doorknob or another person? That is somewhat the way lightning is formed. Think about it this way. When you walk across a carpet you create friction and attract negative charges. Then when you touch a doorknob, the negative charges are attracted to the positive charges in the doorknob and that creates a small spark.

What is a thunderstorm?

A simple explanation is a thunderstorm is any storm that produces thunder. But, it is much more than that. Thunderstorms are a complicated mix of water, ice, wind and heat. There are several ingredients that a thunderstorm needs to develop. A thunderstorm needs moisture to form clouds and rain, unstable air, warm air that can rise rapidly through cooler air in the atmosphere and lift. Lift could be mountains, heating from the sun, or cold or warm fronts. Some meteorologist, look at thunderstorms as a cooling engine for the Earth. The thinking is that a thunderstorm is a huge natural pump. Think of it this way, high up in the atmosphere say 30, 40 or 50 thousand feet up, close to the top of some of these storms, the air can be as cold as 90 to 100 degrees below zero! That's cold! At the same time, especially on a hot summer day, temperatures here on the ground can be 90 to 100 degrees above zero. Thunderstorms can move this heat on the surface of the earth up into the upper levels of the atmosphere quickly. This is called "convective heat transport". Without thunderstorms some scientists and meteorologist estimate that the mean temperature of the earth could rise as much as 20 degrees. That would make it impossible to live in certain areas of our planet.

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