Tropical cyclones are intense low pressure areas that form over tropical and subtropical waters. They have organized thunderstorm activity and winds circulating counterclockwise in the northern hemisphere. Factors like warm ocean waters and low wind shear allow the storms to develop vertically. Impacts of tropical cyclones include heavy rain, strong winds, storm surges, and tornadoes that can cause damage to infrastructure, agriculture, and loss of life. During cyclones, precautions such as evacuating low-lying areas, securing property, and listening to weather warnings are important.

1. TROPICAL
CYCLONES
CLASS 9 SOCIAL STUDIES
PROJECT WORK F.A.-3,
TOOL-1

2. WHAT ARE CYCLONES ?
Cyclone refers to any spinning storm that rotates around a
low-pressure center. The low-pressure center is also referred
to as the 'eye' of the storm, which is well known for being
eerily calm compared with the areas under the spinning
'arms' of the storm.
Here are the types of cyclones :
Tropical cyclones
Polar cyclones
Mesocyclones

3. IN THIS POWER POINT PRESENTATION WE ARE GOING TO
DISCUSS IN DETAIL ABOUT TROPICAL CYCLONES.
WHAT IS TROPICAL CYCLONE ?
A TROPICAL CYCLONE IS AN INTENSE LOW PRESSURE AREA OR A WHIRL IN THE
ATMOSPHERE OVER TROPICAL AND SUB-TROPICAL WATERS
• WITH ORGANISED CONVECTION I.E. THUNDERSTORM ACTIVITY
• WINDS AT LOW LEVELS, CIRCULATING ANTI-CLOCKWISE IN THE NORTHERN HEMISPHERE
AND CLOCKWISE IN THE SOUTHERN HEMISPHERE
• PRESSURE INCREASES OUTWARDS FROM THE CENTRE OF A CYCLONIC STORM.
• THE AMOUNT OF THE PRESSURE DROP IN THE CENTRE AND THE RATE AT WHICH IT
INCREASES OUTWARDS GIVES THE INTENSITY OF THE CYCLONES AND THE STRENGTH
OF WINDS.

4. Mechanism of tropical cyclones
A source of warm, moist air derived from
tropical oceans with sea surface
temperature normally near to or in
excess of 27 degrees C.
Winds near the ocean surface blowing
from different directions converge and
cause air to rise and storm to form
clouds.
Winds which do not vary greatly with
height are known as low wind shear. This
allows the clouds to rise vertically to high
levels.
Coriolis force i.e. the spin induced by the
rotation of the earth is one of the main
factor. Once a cluster of storm clouds
start to rotate, it becomes a tropical
depression. If it continues to develop it
becomes a tropical cyclone and later a
cyclone.

5. This map represents the
states of India and the
level of impact affected by
all of the states. The
following represents:
Deep red – Most
vulnerable
Red and pink –
Average impact
Yellow – Low impact

6. Factors that contribute to cyclones
A fall in the atmospheric pressure over the sea surface
Effect of the wind
Influence of the sea bed
A funneling effect
The angle and speed at which the storm approaches the coast
The tides

7. EFFECTS OF CYCLONES
THE MAIN EFFECTS OFTROPICAL CYCLONESINCLUDEHEAVY RAIN,STRONG WIND,LARGESTORM SURGES AT
LANDFALL,ANDTORNADOES. THE DESTRUCTION FROM TROPICAL CYCLONEDEPENDSMAINLYONITSINTENSITY,
SIZEANDLOCATION.
They harm the ecosystem of the surrounding region.
Civic facilities and communication systems are disturbed.
They causes harm to plant human and animal life.
Agricultural land is severely affected, especially in terms of
water supply and soil erosion
They cause damage to the life and the property of the
people and the government

8. Weather phenomenon are studied with the following processes and
instruments:
1. Surface level observations: Helps to find out the pressure,
temperature, density and viscosity with altitude in the Earth’s
atmosphere. Surface weather observations are taken at airports
for safety concerns during takeoffs.
2. Upper level observations: Helps to find the rate of atmospheric
pressure, temperature, humidity and wind speed. Pilots and air
force are benefitted from this upper level observations.
3. Single Stevenson screen: The purpose of this is to provide a
standardized environment to measure temperature, humidity,
dew point and atmospheric pressure.

9. 4. Thermo-Hygrograph: Measures and records both temperature and
humidity or dew point. Thermo means temperature and Hygro
means Humidity. It measure the maximum and minimum
temperature in a day.
5. Self recording rain gauge: It measures the amount of precipitation
in a certain amount of time. It is nothing but it measures rainfall.
It is measured in millimeters.
6. Open pan evapori meter: This instrument measures the rate of
evaporation in a particular area. Open pan evapori meter
measurements enable farmers and ranchers to understand how
much water their crops need. This helps to increase the rate of
production.

10. If I were a fisherman in the coast of Machilipatnam :
I am a fishermen in Machilipatnam, a place frequently affected by cyclones.
My income wholly depends on fishing. Fishing is a very risky occupation.
Whenever we go to sea we never think whether we can return safely, so we
should be very careful. I frequently watch and listen weather forecasts
through radio and television. Now a days due to the technological
development, we have got fishing apps which help us to know the sea
movements. We even get alerts from the government. Everyday before going
to fishing all the fishermen get to gather to discuss about the sea condition
so that illiterates and people who can’t avail such facilities can also be benefitted.
The precautions we take during cyclones :
1.We don’t go for fishing during cyclones. We go for fishing, only if we come to
know that there is no danger in fishing.
2.We keep a note of all the warnings given by the Meteorological Department.
3.We keep emergency phone numbers of police, ambulance and fire brigade
handy.
4.We vacate the place immediately if the condition of the cyclone is worse.

11. If I were a pilot in Visakhapatnam :
I am posted as a pilot in Vizag, the first place affected by the deadly Hudhud cyclone.
Air transport is the most comfortable and fastest means of transport. Air transport
is uncertain and unreliable as it is controlled to a great extent by weather conditions.
There are many flight accidents taking place. To avoid this, the government takes many
precautions. We receive online real-time data on weather updates on-board a flight
with from the Aviation Weather Observation System. We receive weather and
turbulence forecasts once aloft, we get periodic updates from the meteorologists and
we have a weather radar in the cockpit. We should attend the classes in India
Meteorological Department to interpret the weather forecast code.
Precautions to be taken by us during cyclones :
1.If the cyclone is going to hit the plane, we should not panic, instead find the way
to escape the cyclone and listen to the alerts carefully.
2.Give instructions to the passengers not to panic and prepare them to handle the safety kit.

12. If I were a resident in the low lying area of Orissa :
I am a resident in the low lying area of Orissa, a place lashed
by cyclones. I need to be very careful and cautious to avoid the
destruction of life and property. To know the weather conditions
I read day to day weather forecast from newspapers and also
watch television. I am very thankful to the India Meteorological
Department which sends SMS to those who register their names in
the official website.
Precautions we take during cyclones :
1.We do not venture outside until we are advised to do so.
2.We keep a stock of non perishable food items and fill water in
buckets and cover them.
3.We keep listening to the media for regular updates.
4.Based on the predicted wind and storm surge heights, we may
evacuate the place if necessary.

13. If I were a community rescue worker in West Bengal :
I am a community rescue worker in West Bengal, a place lashed
by cyclones. I work for the society. West Bengal is often hit by
cyclones. To know the weather conditions in this place I go with
media (radio, t.v., newspaper). I have internet facility at my home.
I opt online weather forecast. Our Association gets alerts from
the India Meteorological Department.
Precautions taken by us during cyclones :
1.We should ensure that all the people in the community
know that cyclone is going to hit the place.
2.We take immediate steps shall be taken to conduct mock
drill in every cyclone and flood shelter.
3.In worst conditions we should be able to evacuate everyone
from the place.

14. DO’S AND DON’S DURING CYCLONES
Do’s
1.We should regularly listen to weather bulletins on television and radio.
2.It is necessary to have an emergency kit ready at home.
3.We should ensure that the house is strong enough to face the cyclone.
4.We should have the phone numbers of hospitals, police, help agencies, relatives, friends.
5.We should store enough non-perishable food items in waterproof bags.
6.We should disconnect all the electrical appliances.
7.Based on the predicted wind and storm surge heights, an evacuation may be necessary.

15. Don’ts
1.We should not venture outside especially into sea.
2.We should avoid being mislead by rumors.
3.Don’t touch the loose and dangling wires as it may lead to current shocks.
4.We should not ignore warnings and avoid sightseeing.

16. Field trip questionnaire
1.What are the different types of parameters?
Wind speed and direction, air temperature, air pressure, air humidity, precipitation,
haze and contents of the air, solar and terrestrial radiation.
2.What is the difference between forecast and nowcast?
Forecast :Weather forecasting is the application of science and technology to
predict the state of the atmosphere for a given location in advance.
Nowcast : A description of present weather conditions along with a short-term
forecast is called nowcast.
3.Name the instrument used to record the variation in humidity and
temperature?
Hygrometer
4.Why is Hydrogen used in place of Helium in balloons for upper level
observations?
Helium’s non-flammable nature makes it the only practical lifting gas for
manned lighter-than-air flight. But it is scarce and expensive. On the other hand,

17. hydrogen is the earth’s lightest element and can be manufactured easily and is
inexpensive. So hydrogen used in place of helium in balloons for upper level
observations.
5.Upper level observations are made in the Troposphere. Why?
The troposphere is the lowest layer of Earth's atmosphere. The troposphere starts at
Earth's surface and goes up to a height of 7 to 20 km. Most of the mass of the
atmosphere is in the troposphere. Almost all weather occurs within this layer. Air is
warmest here. Higher up it gets colder. Air pressure and the density of the air are
also less at high altitudes. This helps the balloon to raise and make observations.
6.Name the different surface level observation instruments.
Maximum and minimum thermometers, Anemometer and wind vane, Dry and Wet
bulb thermometer, Rain gauge and Barometer.
7.How is Hydrogen gas produced in Meteorological Department?
Hydrogen Gas is produced and supplied to all stations in upper air network of IMD,
in cylinders of various sizes. It is produced in the Hydrogen Generation Factory.
Ferro Silicon, Caustic Soda and water are used in this process.

18. 8.What is the full form of RADAR?
Radio Detection And Ranging
9.List the conditions necessary for installing the RADAR stations.
The RADAR station should be installed 30mts away from ground. There should be
no obstruction stopping the electromagnetic waves. Direction is also an important
condition.
1o.Draw a flow chart showing the working of RADAR.

19. 11.How surface level and upper level observations help?
Surface level observations: It helps to find out the pressure, temperature, density,
and viscosity with altitude in the Earth's atmosphere. Surface weather observations
are taken at airports due to safety concerns during takeoffs and landings.
Upper level observations: It helps to find the rate of atmospheric pressure,
temperature, humidity and wind speed. Pilots and air force are benefitted from this
upper level observations.
12.In what ways information gathered through RADAR helps us?
Information given by RADAR is used in the detection of ships, spacecraft, guided
missiles, motor vehicles, weather formations, and terrain. RADAR is used by airport
to ensure the safety of planes and helps to track cyclones.
13.How many observations are made in surface level per day both manually
and automatically?
Manually: 8 observations
Automatically: observations

20. 14.What is the extent of troposphere at the poles and at the equator?
At poles: About 8kms
At equator: About 20kms
15.Which part in human body is used in making the string in Hydrograph?
Human hair
16.Why Stevenson Screen is kept away from sunlight?
Stevenson screens are always installed facing north to keep the sun from shining
directly on the thermometers and affecting the readings. If this instrument is
installed in the east(sun rises) or in the west(sun sets) direction there may be a
increase in the temperature.
17.What are the advantages of automated measurements over manual
observations?
Automated observations Manual observations
No labour is required. Labour is essential to take observations.
Very accurate. Not very accurate.

21. 18.How many weather balloons are launched by IMD on a daily basis?
Two weather balloons are launched by IMD per day.
19.What is the total expenditure involved in launching weather balloons?
Rupees 10,000
20.Why is the government spending huge amounts of money for weather
forecast?
‘Life is more valuable than anything.’ The main aim of government is to protect the
valuable lives of the people. Money as a resource can be brought back with the help
of human resource. But we can’t replace the life of human being with anything. To
protect the human lives from natural calamities such as cyclones, tornadoes,
earthquakes, tsunamis etc. government is spending huge amounts of money for
weather forecast. Because of this government’s initiative we are able to save
millions of lives.

22. Bibliography
I have used the following websites to do this project
India Meteorological Department website
Wikipedia
Cyclone center website
Britannica
I referred ‘Natural Disasters’ book.

23. Done by S. Keerthana