When your clothes rub together in the dryer, they create and store static
electric charge. You may have seen and heard the tiny "lightning" flashes
and crackling "thunder" come from your charged clothes when you pull them
When raindrops and ice particles rub together in a thundercloud, they
create and store a charge in the cloud. When the charge becomes too great
for the cloud to hold, it suddenly discharges with a crackle and flash
which we call thunder and lightning.
You've seen lightning bolts, streamers of charge moving from the bottom
of the cloud to earth. But you may not have seen the streamers which move
the charge from the center of the cloud to the bottom. They are usually
hidden in the cloud. However, they have been photographed and studied.
Scientist call them "J"-streamers. They form a "junction" for the small
pockets of charge scattered throughout the cloud. Like streams and rivers,
they feed charge into the main strokes to ground.
Some interesting lightning facts
Ground strike length: 3-6 miles or more.
Inter- and intra-cloud strike length: from a few yards to 90 miles or more.
Typically 5-10 miles.
Diameter: 0.6-5.0 in. Appears wider because of brightness.
Temperature: Over 50,000 °F averaged over a few millionths of a second.
Surface of the sun is only 11,000 °F.
Air pressure in channel: 100 times atmosphere. This causes thunder.
Occurrences: Average of 8 million ground strikes per day around the world
Current in a strike: Typically 10,000-20,000 amps; can be 200,000 amps
or more. A light bulb uses about 1 amp.
Flash duration: from 1/100 to 2 seconds. A flash consists of 1 to 23 rapid
All About Lightning by Martin A. Uman. Great for both neophyte non-technical
and technical scientific readers.
Lightning by Martin A. Uman. A very thorough examination of all
aspects of lightning. Part of the Advanced Physics Monograph Series.