3. Cyclone refers to any spinning storm that rotates around a low-pressure
Closed low-level atmospheric circulation, strong winds, and a spiral
arrangement of thunderstorms that produce a heavy rain.
Cyclones are characterised by inward spiral winds that rotate about a zone of
low air pressure
Warm core cyclones such as tropical cyclones and subtropical cyclones are
lie within the synoptic scale
Mesocyclones, tornadoes are lie within the smaller mesoscale
Cyclones are also seen on the extra terrestrial planets. Such as Mars,
Cyclones form due to latent heat driven by significant thunderstorm activity
4. TYPES OF CYCLONES
The term ‘cyclone’ actually refers to several different types
of storm. There are three types of cyclones.
1. Tropical Cyclones
2. Polar cyclones
5. TROPICAL CYCLONES
Tropical cyclones are what most people are familiar with
because these are cyclones that occur over the tropical ocean
regions. Hurricanes and typhoons are actually types of tropical
cyclones, but they have different names so that it’s clear where
that storm is occurring. Hurricanes are found in the Atlantic and
Northeast pacific, typhoons are found in Northwest pacific.
6. POLAR CYCLONES
Polar cyclones are cyclones that occur in polar region
like Greenland, Siberia and Antarctica. Unlike tropical
cyclones, Polar Cyclones are usually stronger in winter months.
Mesocyclone is a cyclone that occurs when part of a
thunderstorm cloud starts to spin, which may eventually lead to a
tornado. 'Meso' means 'middle’.
8. Tropical cyclones form only over warm ocean waters near the
• To form a cyclone, warm, moist air over the ocean rises upward from near
the surface. As this air moves up and away from the ocean surface, it leaves is
less air near the surface. So basically as the warm air rises, it causes an area of
lower air pressure below.
• Air from surrounding areas with higher air pressure pushes in to the low
pressure area. Then this new “cool” air becomes warm and moist and rises,
too. And the cycle continues…
• As the warmed, moist air rises and cools the water in the air forms clouds.
The whole system of clouds and wind spins and grows, fed by the ocean’s heat
and water evaporating from the ocean surface.
• As the storm system rotates faster and faster, an eye forms in the centre. It is
very calm and clear in the eye, with very low air pressure. Higher pressure air
from above flows down into the eye.
9. Category Wind Gusts Ocean Swells Damage
1 Up to 125 km/hr
1.2 – 1.6 m Slight
Trees and farmland damaged
2 126 – 169 km/hr
1.7 – 2.5 m Significant
Minor house damage. Severe damage to signs
and trees. Heavy damage to crops
3 170 – 224 km/hr
2.6 – 3.7 m Structural
House roofs and most likely power failures
4 225 – 279 km/hr
3.8 – 5.4 m Significant
roofing and structural
Airborne debris, widespread power failure
5 Winds above 280
km/hr - Very
More than 5.5 m Almost
total destruction and
Houses flattened, cars overturned
• When the winds in the rotating storm reach 39 mph (63 kmph), the storm is
called a “tropical storm”. And when the wind speeds reach 74 mph (119 kmph),
the storm is officially a “tropical cyclone” or “hurricane”.
10. The only difference between a hurricane, a cyclone, and a typhoon is the location
where the storm occurs. Hurricanes, cyclones, and typhoons are all the same
weather phenomenon; we just use different names for these storms in different
In the Atlantic and Northeast Pacific, the term “hurricane” is used.
The same type of disturbance in the Northwest Pacific is called a “typhoon” and
“cyclones” occur in the South Pacific and Indian Ocean.
The ingredients for these storms include a pre-existing weather disturbance,
warm tropical oceans, moisture, and relatively light winds. If the right conditions
persist long enough, they can combine to produce the violent winds.
Difference between Typhoon, Hurricane and
12. • The main source of energy for cyclones is the warm oceans in the tropical
• To initiate a tropical cyclone the sea- surface temperature generally needs
to be above 26.5⁰C however, existing cyclones often persist as they move
over cooler water.
• The development of a tropical cyclone also relies on favorable broad-scale
wind regimes’ and can persist for several days with many quite erratic paths.
They lose their source of energy when they move over land or colder oceans
causing them to dissipate.
• Weakening may also occur if the cyclone moves into an unfavorable wind
regime which disrupts the structure of the system.
• Sometimes a decaying tropical cyclone may interact with a weather system
in higher latitudes to cause impacts far from the tropics.
13. IMPACTS OF CYCLONES
The main impact of cyclone includes heavy rainfall,
strong wind, large storm surges at landfall, and tornadoes.
The destruction from a cyclone depends mainly on its
intensity, its size, and its location after the cyclone has
passed, devastation often continues. Some of the impacts of
The wind from a category one cyclones cause minimal
damage to shrubbery and trees. Category 5 storms are the
most forceful, bringing winds of more than 156mph. Wind
this fact can rip trees from the ground and flatten buildings.
Cyclones that fall in between cause varying degree of
distraction, including tearing branches from trees and
Cyclones can produce flooding in two ways. First, tropical
cyclone frequently causes a surge in ocean waters causing sea
levels to rise above normal. These surges sometimes called
tidal waves, can drown people and animals, and are often the
greatest killer in cyclone. Cyclones also can bring torrential
rains that lead to flooding.
A cyclone’s high wind can erode the soil, there by damaging
existing vegetation and ecosystems. This erosion leaves the
area exposed and prone to even more wind erosion. Sand and
soil that is blown into other areas can damage the vegetation.
15. STORM CHURN
Storm churn happens when a cyclone winds churn up cold
water as it moves across the ocean. This churning lowers the
water temperature after the storm has passed, squelching the
formation of new storms.
16. Fig : Map showing Coastal Areas of India affected by Cyclones
DISTRIBUTION OF CYCLONE IN INDIA
17. • With about 6 percent of the world wide cyclones, the Indian
subcontinent is one of the worst cyclone affected areas of the
• About 8percent of the total land area, particularly along the
eastern coast and Gujarat coast is vulnerable to cyclones.
• Indian Ocean is one of six major cyclone prone regions of the
world. On an average, about 5-6percent tropical cyclones are
formed in the Bay of Bengal and the Arabian sea every year.
• The eastern coast is more prone to cyclones .The total cyclones
generated in the Indian ocean, strike the east coast of India.
• There are two definite seasons of cyclones in the north Indian
ocean. One is from May to June and the other from mid-
September to mid –December
18. SOME SEVERE CYCLONES RECENTLY HELD IN INDIA
1. In West Bengal the cyclone
named Komen held in the year
2015, Roanu in 2016 and
Mora in 2017
2. In Andhra Pradesh the cyclone
named Lehar occurs in the
year 2013, Hudhud in 2014
and Kyant in 2016
3. In Kerala the cyclone named
Nada occurs in 2016 and
Vardah in 2016
19. 4. In Maharashtra the cyclone
named ARB 02 occurs in 1994 and
phyan in 2009
5. In Tamil Nadu the cyclone named
Madi in 2013, Roanu in 2016,
Kyant in 2016, Nada in 2016 and
Vardh in 2016
20. EFFECTS OF CYCLONES
• Cyclones cause heavy rainfall and landslides.
• They cause lot of harm to towns and villages, causing severe damage kuccha
houses. Coastal businesses like shipyards and oil wells are destroyers and cause
many deaths in the ocean and money can also lost if the ship is carrying
• They harm the ecosystem of the surrounding regions.
• Civic facilities are disturbed.
• Agricultural land is severely affected, especially in terms of water supply and
• It cause harm to human, plant and animal life.
• Communications systems are badly affected due to cyclones.
21. • Cyclones are the upper ocean heat content, the vertical shear of the
environment wind, interaction with other weather systems, impact of dry air
• Social costs includes, loss of life and livelihood, loss of crops leading to
• Education and other services destroyed, increased burden government to
rebuild areas affected, and meant for other projects must now be used repair
the damage done by the cyclones.
• Cyclones can make the sewage pipes block up and stop working and
sewage can split everywhere which also causes disease.
22. SAFETY MEASURES OF CYCLONES.
• Check with your local council or your buildings control authority to see if
your home has been built to cyclones standards.
• Check that the walls, roofs and eaves of your home are secure.
• Trim tree tops and branches well clear of your home (get council
• Preferably fit shutters, or at least metal screen, to all glass areas.
• Clear your property of loose material that could blow about and possibly
cause injury or damage during extreme winds.
23. When a cyclone watch is issued
• Re-check your property for any loose material and tie down(or fill with
water)all large, relatively light items such as boats and rubbish bins.
• Fill vehicles’ fuel tank. Check your emergency kit and fill water containers.
• Ensure household members know which the strongest part of the house is
and what to do in the event of a cyclone warning or an evacuation.
• Tune to your local radio/TV for further information and warnings.
• Check that neighbors are aware of the situation and are preparing.
24. When a cyclone warning is issued
• People should evacuate faster as soon as warning is issued
• If requested by local authorities, collect children from school or
childcare centre and go home.
• Park vehicles under solid shelter.
• Put wooden or plastic outdoor furniture in your pool or inside with other
• Close shutters or board-up or heavily tape all windows
25. When the cyclone strikes
• Disconnect all electrical appliances. Listen to your battery radio for
• Stay inside and shelter in the strongest part of the building
• If the building starts to break up, protect yourself with mattresses, rugs or
blankets under a strong table or bench or hold on to a solid fixture, e.g. a
• Beware the calm eye. If the wind drops, don’t the cyclone is over: violent
winds will soon resume from another direction. Wait for the official ‘all
26. After the cyclone
• Don’t go outside until officially advised it is safe.
• Check for gas leaks. Don’t use electric appliances if wet.
• Listen to local radio for official warnings and advice.
• If you have to evacuate, or did so earlier, don’t return until advised. Use a
recommended route and don’t rush
• Beware of damaged power lines, bridges, buildings, trees, and don’t enter
• Do not drink water from unknown sources as it may be contaminated.
28. • Cyclone forecasting involves predicting where a tropical
cyclone is going to track over the next five days, every six
to twelve hours.
• The forecasting has evolved from a single station
approach to a comprehensive approach which uses a variety
of meteorological tools and methods to make predictions.
• The weather of a particular location can show signs of
approaching cyclone, such as increasing swell, falling
barometric pressure, increasing tides and heavy rainfall
29. Benefits of Tropical Cyclones:
Although Tropical cyclones are known for destruction they
cause, when they strike they also bestow certain benefits to the
climatic conditions of that area such as
Relieve drought conditions.
Management of Cyclones:
There are many structural and non-structural measures for
effective disaster management of cyclones. The structural
measures include construction of cyclone shelters, construction
of cyclone resistant buildings, road links, bridges, canals, drains,
saline embankments, surface water tanks, communication and
power transmission networks etc
• Cyclone refers to any spinning storm that rotates around a low-
• Cyclone is a large scale air mass that rotates around a strong
center of low atmospheric pressure.
• Cyclones are characterised by inward spiralling winds that
cyclone is known as tornado, hurricane or as a cyclone
depending on the position and latitude of the cyclone.
• Cyclones are a natural disaster which can be prevented but can
be predicted and the damage reduced.
• The process of Cyclone formation and intensification is
described as cyclogenesis.