Cyclones are spinning storms that form over warm tropical oceans and rotate around areas of low pressure. There are three main types of cyclones: tropical cyclones, polar cyclones, and mesocyclones. Tropical cyclones include hurricanes and typhoons. Cyclones form due to the rising of warm, moist air over ocean surfaces which causes low pressure areas. As surrounding high pressure air moves in, it picks up heat and moisture and the spinning storm system intensifies. Several factors influence cyclone formation and intensity. India experiences many destructive cyclones each year along its eastern and western coasts.

1. CYCLONE

2. WHAT IS CYCLONE
• Cyclone refers to any spinning storm that rotates around a low-
pressure centre.
• 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.
• Meso cyclones, tornadoes are lie within the smaller meso scale.
• Cyclones are also seen on the extra terrestrial planets. Such as
Mars, Neptune.
• Cyclones form due to latent heat driven by significant thunderstorm
activity.

3. 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
3. Meso cyclones

4. 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.

5. 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.

6. MESOCYCLONE
• Meso cyclone is a cyclone that occurs when part
of a thunderstorm cloud starts to spin, which
may eventually lead to a tornado. 'Meso' means
'middle’.

7. FORMATION OF CYCLONES

8. HOW CYCLONES FORM
 Tropical cyclones form only over warm ocean waters near the equator.
 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.
 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”.

9. CYCLONE CATEGORIES
Category Wind Gusts Ocean Swells Damage
1 Up to 125 km/hr -
Gales
1.2 – 1.6 m Slight
damage
Trees and farmland
damaged
2 126 – 169 km/hr -
Destructive
1.7 – 2.5 m
Significant Damage
Minor house
damage. Severe
damage to signs and
trees. Heavy
damage to crops
3 170 – 224 km/hr
Very Destructive
2.6 – 3.7 m
Structural damage
House roofs and
most likely power
failures
4 225 – 279 km/hr -
Very Destructive
3.8 – 5.4 m
Significant roofing
and structural
damage
Airborne debris,
widespread power
failure
5 Winds above 280
km/hr - Very
Destructive
More than 5.5 m
Almost total
destruction and
extremely
dangerous
Houses flattened,
cars overturned

10. CAUSES OF CYCLONES

11. CAUSES OF CYCLONE
 The main source of energy for cyclones is the warm oceans in the
tropical regions.
 They are caused in areas with lower atmospheric pressure.
 Usually, areas located near the equator face cyclones.
 What causes cyclones is the rising of warm air over the ocean
surface.
 Once the warm air rises, the surrounding cool air rushes into this
space.
 The cool air heats up and again rises in the atmosphere.
 This process goes on to take place continuously.
 The rapid rise causes the formation of an eye-like structure in the
center.
 Likewise, the low-pressure area gets continually filled with high-
pressure wind.

12. 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 cyclones are:
 WIND
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.
 FLOODING
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.
 EROSION
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.
 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.

13. DISTRIBUTION OF CYCLONE IN
INDIA

14. AREAS OF CYCLONE IN INDIA
• With about 6 percent of the world wide cyclones, the Indian
subcontinent is one of the worst cyclone affected areas of the world.
• About 8 percent 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.

15. 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, Hud hud
in 2014 and Kyant in 2016.
3. In Kerala the cyclone named Nada occurs in 2016 and Vardah in 2016 .
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.

16. EFFECTS OF CYCLONES
• Cyclones cause heavy rainfall and landslides.
• They cause lot of harm to towns and villages, causing severe damage kuccha
houses.
• They harm the ecosystem of the surrounding regions. • Civic facilities are
disturbed.
• Agricultural land is severely affected, especially in terms of water supply and
soil erosion.
• It cause harm to human, plant and animal life.
• Communications systems are badly affected due to cyclones
• Cyclones are the upper ocean heat content, the vertical shear of the
environment wind, interaction with other weather systems, impact of dry air
and landfall.
• Social costs includes, loss of life and livelihood, loss of crops leading to food
scarcity.
• 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.

17. SAFETY MEASURES OF CYCLONE
• 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 permission) .
• 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.

18. BEFORE CYCLONE
• 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.

19. CYCLONE FORECASTING

20. BEFORE CYCLONE
• 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 loose items.
• Close shutters or board-up or heavily tape all
windows

21. DURING CYCLONE
• Disconnect all electrical appliances. Listen to your
battery radio for updates.
• 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
water pipe.
• Beware the calm eye. If the wind drops, don’t think
the cyclone is over: violent winds will soon resume
from another direction. Wait for the official ‘all
clear’.

22. 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 floodwaters.
• Do not drink water from unknown sources as it
may be contaminated.

23. ADVANTAGES OF TROPICAL CYCLONES
• Heat Balance - Tropical cyclones help maintain the
global heat balance by moving warm tropical air
away from the equator, towards the poles.
• Rainfall – Without a doubt, this is the most
important benefit of a cyclone.
• Sea life - Increased rainfall from cyclones help river
systems by flushing out muds, carving out new
channels and opening up areas to inundation of
the wet lands there by increasing both nesting and
food supplies.
• Relieve drought conditions.

24. 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.

25. CONCLUSION
• Cyclone refers to any spinning storm that
rotates around a low pressure.
•Tropical cyclones present a complex variety of
weather & water hazards.
• Tropical cyclones are often not well
understood.
• They require a considerable amount of
education before & during an event.
• Preparation & planning can help mitigate
losses.

26. THANK YOU