What is a
A hurricane is the most
violent storm known on Earth.
· Hurricanes are tropical storms. They take place between the Equator and the Tropic of Cancer to the north, or
between the Equator and the Tropic of Capricorn to the south.
· Hurricanes form at sea and cause dangerous, stormy
· Some hurricanes reach the land and can destroy buildings
· A hurricane can blow high waves onto the land and cause
· The Atlantic hurricane season lasts from the beginning of
June until the end of November.
· There are usually between four and six hurricanes in a
year that will cause some destruction on land.
The winds in a hurricane
do not blow from west to east or north to south. They blow round in
· A hurricane is like a spinning
· The winds in a hurricane blow in a
· North of the equator the winds in a hurricane blow in an
· South of the equator the winds blow in a clockwise
· The winds in a hurricane blow at a speed of at least 74
miles an hour. Their speed is often much more than
Hurricanes can be seen
from space. This photograph from space shows Hurricane Ivan hitting the coast of
· Hurricanes form a thick mass of swirling cloud which can
be seen from space.
· A hurricane can be six miles high and 400 miles
· An area of calmer weather lies in the centre of the
hurricane. This is known as the ‘eye of the
Why does a
hurricane move in circles?
Hurricanes form their
circular, swirling movement because of the spinning of the earth on
· If the earth did not spin, we would have very strong
winds from the tropics to the poles and back.
· Because the earth spins, the spinning movement causes the
wind to go to the right. Try this yourself. If you keep turning to the right, you will go round in a
· The force that makes the wind turn to the right is called
the Coriolis Force.
· The Coriolis Force does not affect winds above the
· Hurricanes never form on the Equator
What causes a
Hurricanes form in areas
of low pressure. When meteorologists (scientists who study weather)
talk of low pressure, they mean warmer weather, storms and rain.
· In the tropics there is a broad area, or zone, of low
pressure on either side of the equator.
· Inside the area of low pressure the ocean is warm and
heats the air above it.
· The warm air rises until it cools and forms thundery
· As the air rises, more air moves in to replace
· As more and more clouds form and more warm air is pushed
upwards, the clouds join together and begin to spin.
· This is the beginning of the
typhoons and cyclones
Hurricanes, typhoons and
cyclones are the same thing.
· These destructive, swirling storms are known
scientifically as tropical cyclones.
· The cyclones are called typhoons in the north-west
· They are called hurricanes in the Atlantic and north-east
· The word ‘hurricane’ is taken from the name of the Carib
Indians’ storm god, Hunraken.
The names of
(scientists who study weather) know when tropical storms are about to happen. The meteorologists give names to all the tropical storms, hurricanes, typhoons
· The first storm of the year begins with the letter
· The names are male and female in order. For example in 2011 the names of the first six Atlantic tropical storms
· The names are reused every six years, so in 2017
Arlene and Bret will reappear.
· If a storm causes terrible destruction and loss of
life, the name is not used again.
· Following the destruction caused to New Orleans in
American by Hurricane Katrina in 2005, the name Katrina was taken off the list.
· Hurricane Katrina was a category 5
· Category 1 hurricanes have wind speeds of 74 to 95
miles per hour and cause small damage.
· Category 2 hurricanes have wind speeds of 96 to 110
miles per hour and cause moderate damage.
· Category 3 hurricanes cause damage to roofs and trees
and have wind speeds of 111 to 130 miles per hour.
· Category 4 hurricanes are likely to cause some deaths
and extreme damage to buildings and trees. They have wind speeds of
131 to 155 miles per hour.
· Category 5 hurricanes cause death and dreadful
damage. They have wind speeds of over 155 miles an
hour. The result of a category 5 hurricane is often a
An oil rig damaged in a Category 4 hurricane