- What are thunderstorms?
- What causes lightning?
- Storm survival
- Thunderstorm protection
usually happen when the air is warm and humid. Huge cumulonimbus
clouds form in the sky and gusty winds begin to blow. Thunderstorms
always include lightning followed by its noisy companion- thunder.
A thunderstorm often lasts for less then an hour but it produces
the most dramatic type of weather.
occurs when thunderstorms concentrate positive electrical charges
in the upper part of cumulonimbus clouds and negative charges in
the lower part. When the difference in the charge between the top
and bottom of the storm clouds become great enough to overcome air
resistance, a sudden and violent electrical discharge occurs in
the form of a lightning strike or stroke. Although this lasts for
only millionths of a second, the temperature of the stroke rises
to 28, 000 degrees Celsius, which causes the flash and the thunderclap.
>> The formation of lightning.
strokes can have four main effects:
1. People and animals can be electrocuted
2. Material in the path of the lightning strike can be burnt up.
3. The high temperatures of the lightning strike can cause fires
4. Sudden power surges can damage electrical equipment.
can heat the air in its path to 30, 000 degrees Celsius which is
5 times hotter than the Sun's surface. This air expands at great
speed and causes the booming noise we call thunder. Thunder can
be heard at least 16km away. Lightning and thunder happen at exactly
the same time, but you see the lightning before you hear the thunder
because light travels faster than sound.
can work out how far away the thunderstorm is like this: As soon
as you see the lightning, start counting the seconds. Stop when
you hear the thunder, and divide the number you have counted by
three. The answer you get tells you roughly how far you are, in
kilometres, from the thunderstorm.
There are about
16 million thunderstorms a year throughout the world. About 1, 800
storms rage at any moment day or night.
always takes the quickest path to the ground. Tall trees and buildings
are most at risk. Very few people are struck by lightning but it
is dangerous to stand near a tree in a storm. It is safest to be
in a car as the lightning will go into the ground through the rubber
and cities can be badly damaged by storms. Strong winds can lift
the roofs off houses, or destroy buildings completely. Therefore,
in order to reduce the damage caused, tall buildings are fitted
with lightning conductors to carry lightning safely to the ground.
They are also often fitted with anemometers to record the wind speed
at roof level. This information is useful to designers when they
plan new buildings in a city.
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