An Introduction to Thunderstorms

A thunderstorm is a disturbance in the atmosphere that is characterized by lightning and thunder. Lightning is an electrical discharge in the air generated by charged particles in moving air masses. Because lightning is a phenomenon of moving, charged particles, not rain, we see lightning in violent forest fires and volcanoes as well as thunderstorms. Thunder is the sound produced by the shock wave lightning generates. The air immediately around lightning is suddenly heated to high temperatures—up to 30,000°C (54,000°F)—and subjected to high pressure; it expands rapidly. 

Image of cumulonimbus cloudsYou may recognize these clouds as cumulonimbus clouds, which are often seen during a thunderstorm. Photo: Ralph F. Kresge/NOAA


Thunderstorms may be accompanied by gusty winds, heavy rain, sleet, snow, or hail, or by no precipitation at all. A severe thunderstorm can also produce flash floods and tornadoes. Thunderstorms generally move in the direction of overhead winds or in the direction of humid, unstable conditions. Some other key traits of thunderstorms include the following: 

  • Thunderstorms can occur in any location, but are generally in the midlatitudes. In the southeastern United States, thunderstorms occur most often along the Gulf Coast, especially in Florida, which experiences afternoon thunderstorms regularly in summer. 
  • Most thunderstorms occur in the spring and summer months during the warmest part of the day when warm air is most likely to be in motion. Other thunderstorms, for example, in the Central Plains, may occur at night.
  • A well-developed thunderstorm can cover an area as large as 8 –16 square kilometers (5 –10 square miles). You probably recognize these clouds as thunderheads, or cumulonimbus clouds, which are often seen during a thunderstorm. 
  • If the temperature in part of a thundercloud falls below freezing and winds are strong, the raindrops in the storm can develop into hail. Although it is rare, a thunderstorm can occur during winter and may have snow as precipitation. This storm is called a “thundersnow.” 
  • In a fraction of a second, a typical lightning bolt can discharge as much energy as a medium-sized nuclear reactor can in the same amount of time, with currents of up to 160,000 amperes. (Electrical circuits in most buildings carry about 20 amperes.)
  • At any given moment, an estimated 1,500– 2,000 thunderstorms are occurring on Earth. These storms can trigger 6,000 or more lightning flashes per minute.
  • The sound from a thunderstorm travels much more slowly than the lightning flash it produces: 340 meters/second (1,115 feet/ second) for sound at sea level compared with about 3.0 × 108 m/s (about 186,000 mi/s) for light. Consequently, an observer will see the flash of lightning long before hearing the thunder. The time difference between the lightning flash and the sound of thunder can be used, along with the speed of sound, to calculate one’s distance from the storm.



This is an excerpt from the Weather and Climate Systems unit of our curriculum product line, Science and Technology ConceptsTM (STC). Please visit our publisher, Carolina Biological, to learn more. 



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