After you read about the different types of lighning on this page, try the Lightning Quiz to see how much you learned.
Cloud-to-Ground
Cloud-to-ground
lightning is the most damaging and
dangerous form of lightning. It is not the most common type, but it
is the one that is best understood. Most cloud-to-ground lightning
strikes come from the negatively charged bottom of the cloud traveling
to the positively charged ground below. Some cloud-to-ground lightning
strikes deliver positive charges to the ground. Positive strikes are
less common and come from the higher regions of the thundercloud.
Often,
cloud-to-ground lightning bolts strike the highest object, like the
top of a building or the top of a tall tree. The lightning strikes
can cause fire and property damage. If a person is the highest object
in the lightning bolt's path, the lightning may strike the person.
Lightning strikes can cause severe injury or death. Cloud-to-ground
lightning is the best understood type of lightning because it leaves so
much evidence behind.
IntraCloud
Intracloud
lightning is the most common type of lightning. This occurs between
oppositely charged centers within the same cloud. This means that
there are both positive and negative charges within the same cloud.
Usually the process takes place within the cloud and looks like a
bright flash of light which flickers. This bright flash may leave
the cloud and the flash can be visible for many miles.
InterCloud
A less common lightning strike occurs between oppositely charged areas
of different clouds. This means that there are positive and negative
charges within different clouds and the strike travels in the air
between them. This type of lightning is known as intercloud lightning.
Forms
of Lightning
When
lightning appears it can take many different forms and look very different.
Some of these forms are described below.
Forked
lightning
appears as jagged or crooked lines of light. They can have several
branches. Forked lightning can be seen shooting from the clouds to
the ground, from one cloud to another cloud, or from a cloud out into
the air. This lightning can strike up to 10 miles away from a thunderstorm
and appear to be coming out of a clear blue sky. The phrase, "out
of nowhere" or "out of the clear blue" might well describe
some of these forked lightning strokes.
Sheet
lightning
appears as flashes of light that seems to light up or illuminate entire
clouds. This makes the clouds visible far away.
Heat
lightning
is the term used to describe lightning flashes that are too far away
from you to hear the thunder. Heat lightning is created by thunderstorms
that are usually more than 10 miles away. The reason it is called
heat lightning is that it appears most often in the hot summer when
the sky overhead is clear.
Ball
lightning
is very rare. (In fact some scientists say it does not exist at all.)
Reports of ball lightning have been made by passengers on planes and
ships as well as from people that experienced it in their homes. These
form of lightning appears as a glowing ball less than three feet wide.
It lasts from a few seconds to several minutes and then disappears.
Usually there is no damage from ball lightning except for burn marks
left where it traveled through screens or windows.
St.
Elmo's Fire
appears as a blue or greenish glow above pointed objects on the ground.
It was named for the patron saint of sailors. It is created when tiny
positively charged sparks reach up in response to negative charges
in the air or clouds above the ground. Instead of a lightning strike
the glow appears from objects such as a ship's mast, a power pole,
tall antennae, or the wings of an aircraft. If a thunderstorm is nearby,
St. Elmo's Fire might be seen right before a lightning strike.
High-altitude
lightning
has been given other names such as "red sprites," "green
elves," and "blue jets." This form of lightning appears
as brightly colored flashes, high above thunderstorms. These flashes
shoot up above the thunderstorm about the same time as other lightning
discharges inside the storm cloud.
More
about High-altitude lightning can be found at the Red
Sprites and Blue Jets page or at the New Mexico Tech's
Sprite Page.
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Click
the picture above to see a diagram of positive and negative charges
within a cloud and the type of lightning strikes. |
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