- [Narrator] Off in the horizon they rumble.
Rolling across the land, they darken the skies
to then spark fire in the darkness.
Letting out an unmistakable roar.
Thunderstorms are rain showers
accompanied by lightening and thunder.
While violent, these weather phenomena are common
with about 2,000 occurring at any moment worldwide.
There are four major types of thunderstorms.
Single-cell, which are small, weak, and isolated storms.
Multi-cell, a common of type of storm that includes
a cluster of thunderstorms.
Squall line, a collection of storms that form a line
hundreds of miles long.
And supercells, the most intense kind of storm
capable of producing tornadoes.
All thunderstorms form when warm air in the lowest
layers of the atmosphere rises.
Called an updraft, this air causes water
from the earth's surface to evaporate
and carries the moisture upward to form clouds.
The clouds then build and grow.
Sometimes as tall as 10 miles high.
The clouds darken as they fill and become heavy with water.
Cool, dry air from the upper layers of the atmosphere
known as a downdraft then pull this moisture downward
causing it to fall as life-sustaining rain.
In addition to helping sustain life, thunderstorms also help
maintain the planet's balance of energy and electricity.
When energy specifically in the form of heat causes water
to evaporate, the heat is carried upward
with the water vapor.
As the vapor condenses and forms water droplets
it releases the heat into the higher altitudes
of the atmosphere and cools the earth's surface.
Thunderstorms also help regulate the electrical balance
between the atmosphere and the planet.
As clouds in a thunderstorm develop,
excess positive and negative charges form within them.
At a certain point, this buildup of opposite charges
leads to the transfer of electrons
in the form of lightening.
This transference of electricity occurs so quickly
that it breaks the sound barrier.
A phenomenon that produces thunder.
While thunderstorms are necessary
for maintaining balance in the atmosphere,
they can also be hazardous.
(phone line beeping)
Lightening strikes create fires.
Excessive rainfall can cause flash flooding
and high speed winds from tornadoes can destroy homes.
Meteorologists study weather systems to try to predict
the occurrence of thunderstorms and help ensure the safety
of countless communities.