Thunderstorms:
General Information
Dark clouds sometimes bring more than just rain; sometimes
they bring a thunderstorm. Usually these clouds are tall and dark,
and along with the rain there is thunder and lightning. It is
important to understand thunder and lightning so that you will not
only be safe during a thunderstorm, but that you will let go of
your fears of these powerful acts of nature.
Lightning is essentially a giant spark of electricity in the
sky. Lightning is very powerful, and it can cause much damage
when it strikes. In fact, a single bolt of lightning is about 5,000
degrees, much hotter even than the surface of the sun!
Before we can learn about lightning, we much first
understand how positive and negative charges work. Think about
two magnets, and remember that opposites attract. That is,
magnets with the same charge repel each other, but magnets with
opposite charges are attracted to each other. Electric charges
work the same way. Positive electric charges are attracted to
negative electric charges. Negative charges are called electrons.
Within a rain cloud, there are millions of tiny water droplets
and ice crystals swirling around. As they move about, the water
droplets are blown up to the top of the cloud, where it is so cold
that they freeze into hailstones. These hailstones are heavier
than the tiny ice crystals, so they fall to the bottom of the cloud.
The wind causes the hail to bump into each other, which gives it a
negative charge. The tiny ice crystals at the top of the cloud are
left with a positive electric charge. Because the charges inside of
the cloud are out of balance, something has to happen!
When the positive and negative charges inside a cloud are
out of balance, nature forces the charges to move. The negative
electrons in the bottom of the cloud are quickly pulled to the
positive particles in the top of the cloud. The stream of electrons
moves so fast that it cause a sudden burst of light and heat,
which we call lightning. A lightning bolt can be miles long and can
contain 156 quintillion electrons!
There are several different kinds of lightning. The type of
lightning we have just described is contained within a cloud.
Sometimes we call this kind of lightning heat lightning because it
often occurs on a hot summer night. From a distance, this heat
lightning lights up the clouds like a flashlight. Heat lightning is
not dangerous, because it is contained up in the sky.
There is a type of lightning that is very dangerous, and it
causes lots of damage each year. This type of lightning is cloudto-ground lightning, and it strikes the ground or objects on the
ground. The cloud-to-ground lightning occurs when a positive
charge builds up on the ground. This causes the negative
electrons in the cloud to discharge to earth. Most of the time,
lightning strikes tall objects like trees and tall buildings. You
should always be very careful when you are in a storm that
produces cloud-to-ground lightning.
There are several types of lightning that very rarely occur.
One is ribbon lightning, a beautiful and unusual form of lightning.
Ribbon lightning sometimes happens during a windy storm. The
wind causes the lightning channel to spread out, and the result is
that the lightning looks like a wide, striped ribbon. The other
unusual type of lightning is called ball lightning. Ball lightning looks
like a glowing ball about the size of a melon, and it is quite
mysterious. It moves unpredictably, then it disappears,
sometimes with a loud BANG!
Have you ever wondered what causes thunder during a
thunderstorm? Although the sound of thunder can be scary, it is
only lightning that is dangerous. Thunder is caused be a flash of
lightning. When the lightning moves through the air, it heats the
air rapidly. The heated air expands so quickly that it explodes
with a loud noise. The expanding air that causes thunder is similar
to the POP you hear when you open a can of soda, only on a MUCH
smaller scale.