of discharges reach the ground with the remainder being cloud-to-cloud lightning.
A ground strike establishes a connection with Earth’s surface and there are usually
multiple round trips transferring large numbers of electrons back and forth.
Thunder is the explosion of atmospheric gases as the lightning passes through.
Temperaturesinstantaneously reach several times the surface temperature of the
sun and cause an explosion of gases. The gases become so excited that they emit
intense light for a fraction of a second. The explosion triggers a sonic shock wave
that is heard as thunder. Thunder is not usually heard more than a few kilometers
from the storm. At night, “heat lightning” is sometimes visible; this is regular light-
ning but the observer is too far away to hear the thunder. Lightning strikes are
dangerous and kill more people per year in the United States thanhurricanesor
tornadoes. The combination of explosionsand electrical charges are frequently
fatal to living organisms. However, the atmosphere is an exceedingly poor conduc-
tor of energy so that damage is minimal with any distance from the strike.
There are several types of significant thunderstorms that can be differentiated
from air mass thunderstorms. The National Weather of the United States defines342 Thunderstorms
Supercell thunderstorms are caused by unstable conditions in the atmosphere that create very high
temperature differences between the cloud and the surrounding air. Extremely high rotational
speeds within the supercell are common and when downdrafts occur they can cause flash floods,
tornadoes, or hailstorms. (NOAA)