Tropical and Temperate Cyclones

UPSC Geography Questions on Tropical and Temperate Cyclones:

Que 1. Explain the origin, distribution and characteristics of the tropical cyclone.
Que 2. Make a comparative study of the temperate and tropical cyclones.
Que 3. Que. Compare and contrast tropical cyclones and temperate cyclones.
Que 4. Discuss critically the characteristics of the tropical cyclones and analyse the extent to which differ from the temperate cyclones.
Que 5. Discuss the tropical cyclones and analyze the differences between tropical and temperate cyclones.  

Cyclones ~

                  These are define as irregular wind movement having low pressure in centre and high pressure at peripheri. These are associated with destructive and violent weather condition that is very high amount of rainfall along with wind velocity.

Condition for Tropical and Temperate Cyclones Formation ~

• Differential heating of land and sea.

• High-speed winds rotating around a low pressure area.

• Calm area at eye/centre of the cyclone and high speed wind at periphery.

• Cyclones can only occur beyond 5 degree latitudes.

• The energy sources are latent heat of condensation and air masses.

• Cyclone move cyclone in Northern hemisphere is anticlockwise and in Southern hemisphere is clockwise.

Two types of Cyclone ~ 

1. Tropical Cyclones

2. Temperate Cyclones

1. Tropical Cyclones ~

                                  Tropical cyclones are are violent storms that originate over ocean in tropical areas and move over to the coastal area bringing about large-scale destruction caused by violent winds, very heavy rainfall and storm surges. This is one of the most devastating natural calamities they are known as cyclone in the Indian Ocean. Hurricane in the Atlantic, Typhoons in the Western Pacific South China sea, and Willy willies in the Western Australia.

Tropical cyclone founded in between 5 degree north and South to 25 degree north and South latitudes. Its covers smaller geographical area and velocity is very high in general 200 to 400 km per hour/ it can be increased upto 1300 km per hour.

Characteristics of Tropical Cyclone ~

* The Central area of tropical cyclone is known as 'Eye' of the Cyclone.

*The diameter of tropical cyclone varies from 150 to 500 km and vertically from surface to about 12 km.

* The isobar of tropical cyclones are circular in shape and pressure gradient is very steep.

* Tropical cyclones move from east to west under the influence of trade wind.

* They give torrential downpour.

* In tropical region give very high rainfall in shorter time.

* The centre of tropical cyclone is known as 'Eye' of cyclone where the rainfall wind clouds are ineffective.

* Tropical cyclone source of energy is latent heat of condensation.

* Tropical cyclone source fever variety of clouds for example cumulonimbus ☁️.

* Tropical cyclone not marked by distinct stages and destructions or dissipation comes with encounter cold current are land mass.

* Tropical cyclones move from east to west due to trade wind.

* They occur in Northern hemisphere in the autumn season.

The favourable condition for formation of Tropical Cyclones ~

• Large sea surface with temperature higher than 27 degree Celsius.

• Presence of the Coriolis force.

• Small variations in the vertical wind speed.

• A pre-existing weak-low-pressure area or low-level-cyclonic circulation.

• Upper divergence above the sea level system.

Stages of Development of Tropical Cyclone:

As per the criteria adopted by the World Meteorological Organisation (W.M.O.), India Meteorological Department classifies the low pressure systems in to vary classes based on wind speed.

1. Tropical Disturbances

2. Tropical depressions Low winds with a speed between 31 and 61 km ph.

3. Tropical cyclone wind speed from 62 to 88 km ph and it is assigned a name.

4. Severe Cyclonic Storm (SCS) wind speed is between 89 to 118 km ph

5. Very SCS wind speed between 119 to 221 km ph and

6. Super Cyclonic Storm when wind exceeds 221 km ph.

Origin of Tropical Cyclone:

Tropical cyclones have certain mechanism for their formation. These are

A source of warm, moist air derived from tropical oceans with sea surface temperature normally near to or in excess of 27 °C. 

Structure of Tropical Cyclone:

Wind near the ocean surface is blowing from different directions converging and causing air to rise and storm clouds to form.

Winds which do not vary greatly with height are known as low wind shear. This allows the storm clouds to rise vertically to high level;

Coriolis force is induced by the rotation of the Earth. The mechanisms of formation vary across the world, but once a cluster of storm clouds starts to rotate, it becomes a tropical depression. If it continues to develop it becomes a tropical storm, and later a cyclone/ super cyclone.

Landfall:

The condition at which the eye of the tropical cyclone crosses the land is called ‘Land fall’ of the cyclone.

Regional Name of Cyclones ~ 

* Willy-Willes - Australia

* Typhoon - China and Japan

* Hurricane - USA

* Tornadoes -  USA / Caribbean Sea

* Tropical Cyclone/ Chakrawat - India

* Baguio - Philippines

* Taifu - Japan

Despite the huge loss of property, animals and human life during the cyclone, there are some advantage of tropical cyclones ~
• The streams are flushed of pollution.
• They add moisture to dry soil conditions.
• The local water bodies are restored.
• These Precipitation help to maintaining the water budget
• The rainfall recharges ponds, lakes underground water table.

Mind Map of Tropical Cyclone

Temperate / Extra Tropical Cyclones ~

The cyclone formed in the mid latitudes is called as temperate cyclone. As they are formed due to movement of air masses and front, they are called as ‘Dynamic cyclone’ and ‘Wave cyclone’. This cyclone is characterised by the four different sectors, which are varied with their weather patterns.

The system developing in the mid and high latitude beyond the tropic are called mid latitude / extra-tropical cyclones / temperate cyclone the passes of front causes abrupt change in the weather conditions over the area in the middle and high latitudes.

Formation of Temperate Cyclone:

Temperate cyclones form along the polar front. Initially the front is stationary in the Northern hemisphere, warm air blow from the south and cold air from the north of the front. 

When the pressure drops along the front, the warm air move northwards and cold air move towards, south setting in motion an anticlockwise cyclonic circulation. 

The cyclonic circulation lead to well developed extra tropical cyclone, with a warm front and a cold front. 

There are pockets of warm air are from sector wadged between the forward and rear air or cold sector. The warm air glide over the cold air and a sequence of clouds appear for the sky ahead of warm front and cause precipitation. 

The cold front approaches the warm air from behind and pushes the warm air up. As a result, cumulus clouds developed along the cold front. The cold front move faster than the warm front ultimately overtaking the warm front the warm air is completely lifted up and the front is occluded and the cyclone dissipate.

Structure of Temperate Cyclone

Characteristics of Temperate Cyclone ~

* Discover a larger area and can originate over the land and sea.

* Temperate cyclone founded in between 35 degree north and South to 65 degree north and South.

* The velocity of wind of temperate cyclone is 40 to 60 kilometre per hour.

* Temperate cyclones isobars are V-shaped and pressure gradient is gentle.

* Temperate cyclone exhibit variety of clouds development e.g. cumulus, stratus etc.

* Temperate cyclones move from west to east.

Stages in the Formation of Temperate Cyclone:

a. Frontogenesis –Formation of front due to collision of two contrasting air masses.

b. Cyclone genesis – Formation of cyclone due to conversion of fronts into various sectors.

c. Advancing Stage – The stage where cold front advances towards warm front.

d. Occlusion stage - The stage where the cold front over takes warm front

e. Frontalysis – The last stage where fronts disappear and cyclone ends its life.

Most Cyclone Prone Countries ~

1. Cuba : Hurricane

2. Madagascar : Tropical Cyclone

3. Vietnam : Typhoon

4. Taiwan : Typhoon

5. USA (including Hawaii) : Hurricane

6. Australia : Tropical Cyclone

7. Mexico : Hurricane

8. Japan : Typhoon

9. China : Typhoon

10. Philippines : Typhoon

11. Chakrawat : India

Differences between Tropical and Temperate Cyclones :

* Origin -

Tropical cyclone originate mainly in sea during the summer,

Temperate cyclone originate in both on land and water mainly in winter.

* Shape & Pressure Gradient -
The Isobar of tropical cyclone are circular and pressure gradient is very steep.
Temperate cyclone isobars are V-shaped and pressure gradient is gentle.

* Size -

The size of Tropical cyclones are smaller.

Temperate cyclones are spread out in 1000 of kilometres.

* Moving Direction -

Tropical cyclone moves from east to west under the influence of trade wind.
Temperate Cyclone move from west to east under the influence of westerly.

* Wind Velocity -
The Wind velocity of tropical cyclone is higher (200 kilometre per hour to 300 km per hour, which may increases up to 1200 km per hour).
While temperate cyclone wind velocity is lower (40 to 60 km per hour).

* Rainfall -
Tropical cyclone give torrential rainfall in shorter time.
Temperate cyclone give lower rainfall continue for many days.

* Source of Energy -
Tropical cyclone source of energy is latent heat of condensation.
Temperate cyclone source of energy is different in density of air masses.

* Front Formation -
In tropical cyclone front formation not indispensable.
In temperate cyclones friends formation is dispensable.

* Atmospheric Relation -
the relationship of tropical cyclone with upper atmosphere is not very clear.
The relationship of temperate cyclone is very clear with upper atmosphere that is jet stream.

* Latitudes -
Tropical cyclone which are found between 5 degree North and South to 25 degree North and South.
Temperate cyclone found between 35 degree North and South to 65 degree North and South.

* At Centre -

The centre of tropical cyclone is known as the 'eye' of the cyclone where the rainfall and wind are ineffective.

While Temperate cyclone maximum activities at centre with heaviest rainfall.

* Distruction -

Tropical cyclone is more destructive than temperate cyclone.

* Upper Atmosphere -

The relationship of Tropical cyclone with upper atmosphere is not very clear.

The relationship of Temperate cyclone is very clear with upper atmosphere e.g. Jet Stream.

* Cloud Formation -

Tropical cyclone shows fewer variety of cloud.

Temperate cyclone exhibit variety of cloud development.

3 Prime category for Cyclone Management ~

1. Pre- Phase -
* Prevention
* Mitigation
* Preparedness
These steps taken before the the natural hazard of Cyclones. It include long-term prevention measures like construction of embankment to prevent flooding increasing plantation for reducing occurrence of landslide & sound environment management.
cyclone can also be mitigate through various short-term measures which either reduce our modify the scale and intensity of the thread improve the durability and capacity of elements at risk, e.g. proper maintenance of drainage system, better awareness and public education to reduce the risk of hazards, etc.

2. During Cyclones -
* Evacuation
* Search
* Rescue
During the cyclone, require speedy response to elevate and minimise suffering and losses. The evacuation, Search and rescue followed by provision of basic needs such as food clothing, shelter, medicine, and other necessity essential to bring the life of effective community back to degree of normalcy.

3. Post Cyclonic Phase -
* Recovery : to achieve early recovery and reduce vulnerability and future risk.
* Rehabilitation : includes provision of temporary public utilities and housing as interim measure to assist long-term recovery.
* Reconstruction : include construction of damaged infrastructure and habitats and enabling sustainable livelihoods.

Also Read : Cyclone Management