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Cyclone Cycle

A circulation system of a cyclone undergoes a series of stages as it escalates into a mature tropical cyclone. The storm initiates as a tropical disturbance, which generally takes place when loosely organized cumulonimbus clouds in an easterly wave begin to show signs of weak circulation. The storm is classified as a tropical depression once the speed of the wind increases to 36 km (23 miles per hour). If the circulation continues to intensify and wind exceeds 63 km (39 miles) per hour, the system is considered a tropical storm. The storm is classified as a tropical cyclone as the maximum speed of wind exceeds 119 km ( 74 miles) per hour.


Cyclone Stages

The development cycle of tropical cyclones is divided into three different stages. Let us look at the cyclone stages in detail:


Formation and Initial Development Stage

  • The formation and initial development of cyclone storms rely upon the transfer of water vapor and heat from the warm ocean to the overlying air, primarily through evaporation from the sea surface.

  • It encourages the formation of massive vertical cumulus clouds due to the convection with the conduction of rising air above the ocean surface.


Maturity Stage

In the cyclone maturity stage, the waves that form during the formation stage grow as the warm air replaces the spaces behind the moving cold front, and the organization of both cold and warm fronts increases. The cold front in the maturity stage moves much speedily than the warm front, intensifying the circulation of cyclones. The system's lowest pressure is placed at the centre of the wave, and the cyclone's winds are the strongest about 8 miles above the ground.


Modification and Decay

  • A tropical cyclone begins to weaken concerning its central pressure, internal warmth, and extremely high speed as soon as its source of warm moist air initiates to ebb or abruptly cut off.

  • This occurs after its landfall or when it passes over cold water.


What is a Hurricane?

A hurricane is an enormous storm. A massive hurricane storm can be up to 600 miles across and have strong winds both inside and outside at speeds of 75 to 200 mph.  Each hurricane lasts for a week, moving 10 -12 miles per hour over the oceans.  Hurricanes collect heat and energy when in contact with ocean warm waters.  Evaporation from seawater increases their power. Hurricanes rotate in a clockwise direction in the southern hemisphere and a counterclockwise direction around an “eye” in the Northern hemisphere. The calmest part is the centre of the ‘eye’ or storm. It has only light winds and sterling weather. When the hurricane comes into the land. The massive rain, the strong winds, and large waves can cause great damage to buildings, trees, and cars.

The hurricane's scientific name is Tropical Cyclone. Tropical cyclones go by different names. In North America, and the Caribbean, they are known as “Hurricanes” whereas in Indian oceans, they are known as “Cyclones” and in Southeast Asia, they are known as “Typhoons”. 


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Where Do Hurricanes Come From?

Hurricane cyclones, also known as tropical cyclones, come from warm ocean water of 80º F or warmer. The air must cool off very quickly as it goes higher. Also, the wind must move in a similar direction and at a similar speed to force air upward from an ocean surface. The wind blows outwards above the storm allowing the air below to rise. Hurricanes generally form between 5 to 15-degree latitude north to south of the equator. The Coriolis force is required to create the spin in the hurricane and it becomes too weak near the equator, and so the hurricane cyclone never came here.

The hurricane or tropical cyclone is divide into the following stages:


Hurricane Stages

Tropical Waves

A low pressure trough moving generally through westwards along with the trade winds

Tropical Disturbance

An organised area of thunderstorms that usually occurs in the vapour tropics. Generally, they maintain their identity for 24 hours and are accompanied by massive rains and gusty winds

Tropical Cyclones

A  generic term for any organized low pressure that emerges over tropical and sometimes subtropical waters. Some of the examples of tropical cyclones are tropical depression, tropical storms, and hurricanes

Tropical Depression

An organized region of low pressure in which sustained winds are 38 mph or less.

Tropical Storm

A tropical cyclone with maximum speed sustained that ranges from 39 to 73 mph

Hurricane

A tropical cyclone with sustained winds of minimum 74 mph


What is Landfall?

A landfall of cyclones is accompanied by strong winds, lashing rains, and rising sea waves that could threaten people and cause damage to property and land.

Hurricanes or cyclones can start losing their energy and speed after hitting the land as they get energy from the warm ocean water. However, this does not take place quickly.

As the cyclone moves over to the land, its wind fields tend to accelerate. Hence, it can affect larger areas than scientists may have estimated. A larger wind field coupled with the coast results in storms and rising ocean waves. 


Did You Know?

  • Hurricanes are also known as cyclones and typhoons, depending on the region in which they occur.

  • Hurricanes north of the equator spin clockwise whereas south of the equator spins anticlockwise.

  • The three main parts of hurricanes are the eyes, the eyewalls, and rain bands.

  • The Bhola cyclone in 1970 was the world's deadliest hurricane. It is estimated that more than 50000 people were killed in that cyclone.

  • The Galveston Hurricane in 1970 was the deadliest United States Hurricane. It is estimated that up to 8,000 US citizens were killed in that cyclone.

FAQs (Frequently Asked Questions)

1. What are Cyclones?

Ans: In meteorology, cyclones are the most intense storm on Earth. A cyclone is a system of wind rotating in a counterclockwise direction in a Northern hemisphere in a low-pressure centre. The swirling air cools and rises, resulting in clouds and precipitation.


There are two types of cyclones namely mid-latitude cyclone and tropical cyclone. The main cause of mid-latitude cyclones is the winter storms in the middle latitudes. Tropical cyclones are also known as hurricanes.

2. What is the Weakest Form of a Tropical Cyclone?

Ans: The weakest form of a tropical cyclone is known as the tropical depression. The tropical cyclone becomes a tropical storm if the depression intensifies such that its maximum sustained wind reaches 39 miles per hour.

3. When Does the Hurricane Season Begin?

Ans: The Atlantic hurricane season begins from June 1 to November 30, but most of the hurricane begins during the fall months. The Eastern Pacific hurricane season starts from May 15 to November 30.

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