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Types of Lightning & Thunder

Lightning is an electrical discharge from a thunderstorm followed by the sound of thunder. According to the leading scientific theory, lightning occurs when the ice particles in clouds develop positive and negative charges creating electrical potential within the cloud and between the cloud and the ground. Millions of volts of electricity build up in the cloud until the air's electrical resistance breaks down and the electricity discharges, moving from positive to negative regions.

Thunder
- Lightning can have a temperature of up to 54,000 degrees --- three times hotter than the surface of the sun. Thunder is an explosion caused by this sudden heating and expansion of the air. It sends out a shock wave in every direction from the source of the lightning, which the human ear perceives as a loud bang, crack or rumble. Light travels faster than sound, so we always see the lightning before hearing the thunder. Sound travels about a mile in five seconds, so measuring the time between the lightning and thunder gives a rough estimate of the distance of the storm.
Cloud-to-Ground
- Though not the most common, cloud-to-ground lightning is the best understood type. Cloud-to-ground lightning typically occurs when the negatively charged portion of the cloud sends a negative charges toward the Earth. As the storm dissipates, the positively charged portion may send a positive charge toward the ground.
Intracloud Lightning
- Intracloud lightning, the most common form of lightning discharge, occurs when electrical charges pass between oppositely charged sections of the cloud. From the ground, this form of lightning resembles a diffused flash of light flickering with energy discharges. The discharge may break the boundaries of the cloud, giving off a flash resembling a cloud-to-ground flash visible for miles.
Intercloud Lightning
- Intercloud, or cloud-to-cloud, lightning occurs when the electrical discharge passes from the charged portion of one cloud to the charged portion of another. The lightning flash fills the empty space between the clouds.
Upper-Atmospheric Lightning
- "Upper-atmospheric lightning" refers to electric discharges that occur in the upper atmosphere above the altitude for ordinary lightning. Some of these phenomena are called elves, sprites and blue jets.
  
  Elves, which occur above areas of active cloud-to-ground lightning, may result from electromagnetic pulses extending into the portion of the atmosphere called the ionosphere.They typically take the form of a very broad flash of light more than 300 miles across that lasts less than a millisecond.
  
  Sprites are reddish emissions resembling jellyfish, carrots and columns. They appear about 60 miles above the cloud top at about the same time as positive cloud-to-ground lightning and last just a few seconds.
  
  Blue jets, often reported by pilots, emerge from the top of thunderclouds and extend upward in narrow blue cones before spreading out and disappearing 25 to 35 miles up. They last mere seconds. Unlike the other phenomena, they are not directly linked to cloud-to-ground lightning.

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