[Geography Notes] on Tropical Cyclone Pdf for Exam

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

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”. 

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

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.