Everything about Cyclones: Formation, Causes and Impact

Information collected by satellites suggests that cyclones generally form in low-pressure zones and over warm intertropical waters. These are gigantic and deadly storms that create havoc and severe damages to life and property.

According to the World Meteorological Organisation approximately 85 tropical storms develop over the warm tropical latitude oceans.

Read on to find everything about the types, causes, occurrence, impact, hazard zones and preventive measures of cyclones in this article.

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What Are Cyclones?

In meteorological terms, a cyclone is a wind system that rotates inwards (counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere) around a strong low-pressure centre.

Generally, when winds rise above 118 kmph, it is known as a cyclone. These rotating winds forming over the Indian ocean and south of the Pacific Ocean are termed as cyclones. In other regions they are usually called by different names such as, typhoons, hurricanes etc.

To understand the severity of cyclones, one must learn in detail about its process of formation and its categories.

How Are Cyclones Formed?

Scroll down to the following section to understand the formation of a cyclone -

Warm and moist air over the ocean rises upward due to less density, leaving less air near the ocean surface,As a result, it starts to create a low-pressure zone.
Due to the surrounding high-pressure areas, air flows into this low-pressure and eventually warms up, forming a cycle.
With the constant heating rising of the warm air and evaporation process, the entire cloud and wind system starts to spin and grow.
With acquiring more speed, the eye of the cyclone starts to form in the centre. This central zone signifies the lowest air pressure area and is calm and clear. Further, the high-pressure air from above flows towards this region.

When the wind’s rotating speed reaches 63 kmph, it is called a tropical storm. However, when wind speed reaches 119 kmph, tropical cyclone formation takes place.

Now that you know the process of formation of a cyclone, let's take a look at the categories of a cyclone.

What Are the Different Categories of Cyclones?

The categories of a cyclone depends on its wind strength. From the following table, you will be able to estimate the damage a cyclone can cause after its landfall, depending on its wind speed.

Category	Wind Speed (in kmph)	Damage at Landfall
1	119-153	Minimal
2	154-177	Moderate
3	178-210	Extensive
4	211-250	Extreme
5	More than 250	Catastrophic

Now, let's find out the causes behind the formation of a cyclone.

What Are the Causes of a Cyclone?

After knowing the answer to your question, "how are cyclones formed?" you might also like to know about why a cyclone occurs or what causes it.

Here are the factors responsible for cyclone formation -

Warm temperature at sea surfaces.
Coriolis force impacts the area that forms a low-pressure zone.
Atmospheric instability.
Increased humidity in the lower to middle levels of the troposphere.
Low vertical wind shear.
Pre-existing low-level disturbance or focus.

Now that you know how cyclones are formed and what causes them, let's look at the types of cyclones that have occurred in India over the years.

Cyclones that Occurred in India Till Now

With respect to the above table, the following list of cyclones have occurred in India over the past few years -

Name of the Cyclone	Type of the Cyclone
Yaas	Severe cyclonic storm over the Bay of Bengal.
Tauktae	Very severe cyclonic storm originating from the Arabian Sea.
Nisarga	Severe cyclonic storm emerging from the Arabian Sea.
Amphan	Super cyclonic storm formed in the Bay of Bengal.
Kyarr	Super cyclonic storm emerging from the Arabian Sea.
Maha	Extremely severe cyclonic storm originating in the Arabian Sea.
Vayu	Severe cyclonic storms originate from the Arabian Sea.
Hikka	Very severe cyclonic storm emerging from the Arabian Sea.
Fani	Extremely severe cyclonic storm originating from the Indian Ocean.
BOB 03	Severe cyclonic storm formed in the central Bay of Bengal
Bulbul	A very severe cyclonic storm emerged from the Bay of Bengal.

Now let’s delve into the impact of cyclones.

Impact of Cyclones in India

If you know how a cyclone is formed, you must know that it is often accompanied by strong winds, torrential rains and storm surge. These three elements causes impact to a great extent in the following ways -

Strong winds cause damages to infrastructure, uproots trees, and lead to other catastrophes.
Torrential rainfall leads to unprecedented floods and damages to houses and buildings.
Due to storm surge, seawater levels rise, and the coastal areas are exposed to flooding.
The rise in seawater level also erodes beaches and embankments.
Severe cyclonic storms resulting in floods can damage vegetation and livestock.
Due to the strong winds and conditions, the soil tends to become infertile.

In addition to this, cyclonic storms result in the loss of human, plant and animal lives and affect the country's economy.

Next up, let's look at the cyclone-prone zones in India.

Cyclone Hazard Zones in India

As per the Indian Meteorological Department, 13 coastal states and Union Territories in India are prone to a cyclone. The eastern coast of India is more prone to cyclonic conditions than the western coast. However, because of the long coastline of India of 7516.6 km both the coasts of India experience cyclonic storms quite frequently.

Among both the coasts, some states are more vulnerable to cyclones than the others. The most vulnerable states in India that are majorly prone to cyclonic impact are as follows -

West Bengal
Andhra Pradesh
Tamil Nadu
Odisha
Puducherry (UT)
Gujarat

People residing in and around the above areas must equip themselves with certain preventive measures to carry out any damage control.

Preventive Measures to Combat Cyclones in India

The National Disaster Management Authority (NDMA) advises individuals to take the following steps to stay safe during cyclones -

It is necessary to stay indoors during a cyclonic storm and keep away from electrical mains.
In extreme situations, one must prepare an emergency kit that is essential for survival.
It is also vital to keep tabs on regular weather forecast updates and rely on official warnings.
In case your house is unsafe, it is advisable to shift before the onset of a cyclone.

Further, in collaboration with the NDMA, the Government carries out proper evacuation measures for fishermen and the coastal dwellers before the cyclone makes landfall.

With a detailed knowledge of how cyclones are formed and their causes, one can take sufficient precautions and avoid the harsh consequences.

FAQs About Cyclones: Formation, Causes and Impact

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How are tropical cyclones predicted?

It is indeed hard to forecast the start of a tropical cyclone but as they develop, they can be predicted. Scientists do so with the help of computer, satellites, and weather radars. Furthermore, scientists are developing modern techniques that can predict where it will hit, where can it change its course and related details.

How long can a cyclone typically last?

A cyclone can generally last for four to seven days, while severe cyclones (category 3 and above) can last up to weeks.

Around what time does tropical cyclones occur?

In the western North Pacific region, the timings are around May to November. In Arabian Sea and Bay of Bengal, it is often during April - June and September – November.