What causes thunder?
Thunder is caused by lightning. Lightning is a stream of electrons (electricity) flowing within or between clouds, or between a cloud and the ground (usually occurring during a thunderstorm). When a bolt of lightning shoots through the atmosphere, it rapidly heats the air up to 50,000 degrees Fahrenheit (five times the temperature of the sun) in a fraction of a second (almost instantaneously). This superheated air rapidly expands thus opening up a little hole (a partial vacuum) in the air surrounding the lightning’s path, called a channel. As the superheated air quickly dissipates it’s heat (cools), the air rapidly collapses (contracts), creating a tremendous shock (compress) wave. This loud cracking sound wave, is what we hear as thunder. The rumbling sound has to do with the sound echoes and reverberates as the vibrations gradually die out over distance. The reason we see lightning before we hear thunder is because light travels faster than sound. Thunder typically can be heard 10 to
Thunder is caused by lightning. The bright light of the lightning flash caused by the return stroke mentioned above represents a great deal of energy. This energy heats the air in the channel to above 50,000 degrees F in only a few millionths of a second! The air that is now heated to such a high temperature had no time to expand, so it is now at a very high pressure. The high pressure air then expands outward into the surrounding air compressing it and causing a disturbance that propagates in all directions away from the stroke. The disturbance is a shock wave for the first 10 yards, after which it becomes an ordinary sound wave, or thunder. Thunder can seem like it goes on and on because each point along the channel produces a shock wave and sound wave.
