...The Science Behind Lightning...

When Thunder Roars…Go Indoors!!!
June 20th to June 26th is Lightning Safety Awareness Week.
Today’s topic:

The Science Behind Lightning


Each spark of lightning can reach over five miles in length, soar to temperatures of 50,000 degrees Fahrenheit, and contain 100 million electrical volts.   At any given moment, there are 1,800 thunderstorms in progress, somewhere on earth.
Ice in a cloud seems to be the key element in the development of lightning. The ice, which is often hail stones rising and sinking in the storm, helps separate the electrical charges like a big battery. Enormous charge differences develop between the base and top of a thunderstorm cloud.
Once a significant charge difference builds up, opposite charges start to collect between the base of the cloud and objects on the earth, like trees, houses, or towers. Charges from the cloud start to work toward objects on the ground in the form of invisible step leaders, or channels through the air. At the same time, leaders move upward from objects on the ground. If and when these meet, an electrical transfer takes place in the created channel. This is the process of a lightning strike.
Sometimes, several discharges pass through that same channel so quickly that all you see is flickering.
Thunder is the sound created from the rapid expansion of heated air that occurs when lightning passes through the channel. Because the speed of sound is slower than the speed of light, you can determine how far away a strike is by counting the seconds between the visible strike and the thunder you hear. Every five seconds between the two relates to a mile away. Hence, a delay of 10 seconds means the lightning is 2 miles away.
For additional information, please check out the NOAA webpage dedicated to lightning information and safety at: www.lightningsafety.noaa.gov

Return to News Archive

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.