2. 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. Mesocylones
3. 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.
4. 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
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’.
6. 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.
7. 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
• 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”.
CYCLONE CATEGORIES
8. What is the difference
between cyclone,
hurricanes and
typhoons?
9. 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 places.
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
Cyclone
10. Hurricane
Is a type of tropical cyclone that forms over
tropical or subtropical waters. It has winds of
74 mph or more. The term hurricane is used if
it originates in the North Atlantic, Central
North Pacific, and eastern North Pacific.
11. Typhoon
Is a mature tropical cyclone that usually
originates in the northwest Pacific. Typhoons usually
have winds speeds of around 118 to 220 kph.
Meteorologist and experts make use of warning
signal devices when they monitor the weather
conditions. These devices help provide information
that is useful for giving early warnings to the public.
12. Warning Signal Devices
1. Weather satellite ground receiving station – this
used to monitor, observe, report, and collect
atmospheric data for preparation and warning related
to typhoons, floods, and other occurrences related to
weather and climate.
13. 2. Weather surveillance radar
This is a device that is used to track typhoons and
cloud masses at a distance of more or less 400 km.
this device is usually placed on top of the building
where it is free from any obstruction.
14. 3. Rawinsonde
It is an electronic device used for measuring wind
speed and direction, pressure, temperature, and
humidity. This device is attached to a balloon as it
makes its measurement in the atmosphere.
15. Public storm Warning System (PSWS)
It use to help warn locals about the possible impact and
damage a typhoon or tropical cyclone may bring. The revised
public storm warning system for each PSWS number, which
ranges from 1 to 5 (with 1 being weakest and 5 the strongest).
16. 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.
Cyclones that fall in between cause varying degree of
distraction, including tearing branches from trees and
destroying vegetation
17. 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. Cyclones also can bring torrential
rains that lead to flooding.
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.
18. 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.
20. • 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
21. 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
