University of Johannesburg
What is a Cyclone?
Defined as a violent storm that is characterized
by high winds which rotates at a calm center of
low atmospheric pressure.
The center has velocity of 50km an hour.
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How a cyclone is formed!!
• A cyclone is a storm that involves the movement of
warm, high-pressure air and cooler, low-pressure air. This
movement of air causes a rotation that picks up speed
and creates a funnel.
Countries that are effected by Cyclones!!!
The countries in the map
which are filled with
yellow color are mostly
effected by Cyclones. That
are Bangladesh, India, Thai
land, Malaysia, Indonesia
Sri lanka, and much more near
to the Indian ocean.
The coastal areas are subjected to severe wind storms and cyclonic storms.
A full-grown cyclone is a violent whirl in the atmosphere 150 to 1000 km across, 10 to 15 km
Gale winds of 150 to 250 kmph or more spiral around the center of very low pressure area.
Torrential rains, occasional thunder and lightning flashes - join these under an overcast black
Through these churned chaotic sea and atmosphere, the cyclone moves 300 to 500 km, in a
day to hit or skirt along a coast, bringing with it storm surges as high as 3 to 12 metres, as if
splashing a part of the sea sometimes up to 30 km inland leaving behind death and
A storm surge is the sudden abnormal rise in the sea level caused by cyclone.
The sea water flows across the coast as well as inland and then recedes back to the sea.
Great loss of life and property takes place in the process.
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• Unlike mid latitude storms that derive their energy from
the contrast between warm and cold air masses. Tropical
Cyclones oceans as water evaporates from the ocean
Cyclones in Pakistan.!!
• Since Pakistan was created 2 cyclones have hit the sindh
coast. The first was in August 1948 and the 2nd in May
1999. This cyclone was about 80 km east of Karachi . In
Karachi some refugees’ tents were blown drown but
there was no other damages.
The History, Structure, Development, and Destruction
What is a hurricane?
develops in the
Wind speeds are >
What causes the damage in a
Flooding of Tar River as result of
Hurricanes Dennis and Floyd
Final Water Level
Rotation and Pressure
In which direction does a hurricane rotate?
Is the barometric pressure inside the hurricane high or low?
Difference between Cyclone and
• Hurricane: a violent wind which has a circular movement,
especially found in the West Atlantic Ocean. A hurricane
is actually a violent storm formed with water which
causes heavy rains and fierce winds and they can cause
flooding of streets and homes.
Cyclone: a violent tropical storm or wind in which the air
moves very fast in a circular direction. They can be
formed over tropical water, bar the Southeast Pacific
and the South Atlantic Oceans.