Cyclone: Definition, Types, Causes & Stages

Cyclones are natural disasters that evolve over warm sea waters and are strong storms that can lead to the loss of property, and human lives. Cyclones are storms that can be subdivided into several degrees of development starting from tropical disturbances and extending to storms of Category 5 – depending upon the temperature, the rotation of the earth, and the Coriolis force. It is therefore important for people to be well informed on the causes, the various types of cyclones, their stages, and measures to be taken during cyclones.

The word “Cyclone” was developed from a Greek word called “Cyclos”, which refers to the coils of a snake. And it was Henry Paddington who coined the word Cyclos. 

Table of Contents

. What is Cyclone?

. How Are Cyclones Formed?

. Types of Cyclones

. Explore Tropical Cyclones Origin in India 

. What are the Various Causes of Cyclones? 

. The 8 Different Levels of a Cyclone

. Explore the Names of Cyclones

. How to stay super safe when a cyclone comes swirling your way?

What is Cyclone?

A cyclone is a large atmospheric system characterized by low pressure at its center and rotating winds that converge inward. Cyclones can lead to severe weather conditions, including strong winds and heavy rainfall. They often form over warm ocean waters, and their intense storms can cause widespread damage through high winds, flooding, and storm surges.

How Are Cyclones Formed?

Cyclones can significantly damage property and lives with high winds, storm surges, and heavy rainfall. They dissipate due to their movement over cooler waters and create adverse weather conditions. Now, let us understand the 4 stages of cyclone formation. 

1. Cyclones are formed over the surface of warm ocean waters. The surface temperature must be at least 26.5 degrees Celsius (80 degrees Fahrenheit). 

2. As warm water rises into the atmosphere, a region with reduced atmospheric pressure is created below. 

3. The warm air that has ascended then cools and condenses to form clouds. The coriolis effect, caused due to the rotation of earth, causes the warm air to rotate in counterclockwise direction in the Northern Hemisphere and clockwise in the Southern Hemisphere. 

4. The rotating clouds continue to increase, powered by warm ocean waters. As a result of the circular pattern of strong winds and heavy rain, a cyclone is formed. 

The centre of the cyclone is calm and clear. It is also known as the eye of the cyclone and is also the place from where the air descends. Around the eye is the eyewall, where the strongest precipitation and winds occur.

Types of Cyclones

There are 4 types of cyclones and they are:

. Tropical cyclone
. Polar cyclone
. Mesocyclone
. Extratropical cyclone

1. Tropical Cyclone

The regions where the tropical cyclone occurs are over the tropical ocean. It is also called hurricanes or typhoons. Hurricanes are few in some parts of the world and are experienced only in the Atlantic and Northeast Pacific. A tropical cyclone can be classified into five groups, based on the level of storm and the wind that it generates.

2. Polar Cyclone

The polar cyclone refers to the cyclone that develops at the high latitudes and is sometimes referred to as the “Arctic hurricane” in the Northern Hemisphere. One of the mechanisms is the heat exchange from water to air and the latent heat release in the form of condensation of clouds. Predicting the polar cyclones may be hard since they take less than twenty-four hours to formulate. Polar cyclones form over the  Arctic and the Antarctic oceans.

3. Mesocyclone

The mesocyclone is one of the most serious thunderstorms. The mesocyclone is present inside the convective storm in the form of swirling or rotating air. Because of the Coriolis force of the Earth’s rotation, the air rises and rotates along the vertical axis. Both of these are aligned in the given hemisphere, which is the direction of this air and low pressure. As a result, the mesocyclone takes place alongside the rotating air within the thunderstorm. 

4. Extratropical Cyclone

The cyclones that evolve in the middle latitude in relation to the frontal boundaries are termed as extratropical cyclones or the mid-latitude cyclones. The winds of the extratropical cyclone are not as strong as those of the tropical cyclone, however, the temperature gradients are steep. For example, the Nor’easter storm is an extratropical cyclonic storm and affects the eastern region of the United States.

Explore Tropical Cyclones Origin in India 

The spiral movements of the cyclone can become extremely powerful and cause winds, rainfall, harsh storms, and devastating damage in the coastal areas. The classification and naming convention of a cyclone depends on the region. For instance, in the Western North Pacific they are known as typhoons while in the Eastern North Pacific they are referred to as hurricanes. In the Southwest Indian Ocean, they are called cyclones.

Depending on the type, cyclones are also classified as typhoons or hurricanes. In India, cyclones occur over the coastlines in both the eastern and western sides. In fact, the Bay of Bengal is one of the most active cyclone basins in the world. Some of the states that get affected by cyclones are include West Bengal, Odisha, Andhra Pradesh, and Tamil Nadu. Although less prone to cyclones compared to the Bay of Bengal, the Arabian sea, which lies on the western side of India also sees cyclones, mainly during pre and post-monsoon periods. States like Kerala and Karnataka are states affected by these cyclones.

Cyclone Fact: Each year about 85 storms form over warm tropical oceans across the globe.

What are the Various Causes of Cyclones?

For cyclones to form, many factors need to come into play. Temperature, the earth’s rotation, the ocean’s surface, and many other factors play an important role in a cyclone’s formation. Cyclones typically form over ocean waters near the equator. The sea’s surface temperature needs to be 26.5°C or higher. When the warm, wet air rises from the ocean’s surface, it leaves an empty space or an area of low pressure underneath it. This empty space or low-pressure area sucks in moist air, which rises and cools. This further forms clouds and releases heat.

This is when the earth’s rotational powers enters. As the earth continuously turns, the air does not rush straight in. It spins around, like water going down a drain and as this spinning air gains momentum, it creates a large-scale circle of wind spinning around. This is also called the Coriolis Effect. The cyclones rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

The Coriolis Effect occurs due to the Earth’s rotation. It makes objects moving in a straight line appear to be curved but it is mostly noticeable in massive movements like air masses and ocean currents. The Coriolis Effect affects many things like weather patterns and influences the rotational direction of cyclones. These are the various causes of cyclone. 

“Cyclones usually form at the 30 degrees north and south latitude. However, the equatorial region remains safe from cyclones due to zero latitude and a lack of Coriolis effect. The larger the Coriolis force, the greater the probability of cyclone incident in warm or heated seawater.”

– Dr. Nurjani, UGM Expert

As a cyclone becomes bigger and intensifies, it undergoes many stages. Gear up to enter the swirling stages of a cyclone!

The 8 Different Levels of a Cyclone 

Hope you caught the cyclone meaning.Cyclones love playing games just like you and play in 8 different levels. Hop on board to understand various the levels of a tropical cyclone.

Level 1 – Tropical Disturbance

The first level of a cyclone begins as a cluster of thunderstorms that form over warm ocean waters. You cannot see any spinning around in this stage.

Level 2 – Tropical Depression

In this level, you can see a spinning pattern with steady winds of up to 61.15 kilometres per hour or 33 knots. A knot is a unit of speed used in maritime and aviation, in which, one knot is equal to 1.852 kilometres per hour and one nautical mile the same as 1.852 kilometres.

Level 3 – Tropical Storm

Hold on tight the game is getting stronger champ!  Now let us learn about the types of cyclones.

As the steady winds reach 34 to 63 knots, the process is referred to as a tropical storm and is given a name at this point. What are tropical cyclones? Tropical cyclones are named by following the rules set at the regional levels. In the Southern hemisphere, which is the Indian ocean and South Pacific, cyclones are named in alphabetical order with women’s and men’s names being alternated.

Level 4 – Type 1 Cyclone

When the steady winds reach 64 to 82 knots, it is known as a Category 1 cyclone in the Southwest Indian Ocean and South Pacific. In this stage, trees and homes are damaged that can also lead to minor flooding cases in the coastal areas. 

Level 5 – Type 2 Cyclone

In this stage, the steady winds reach 83 to 95 knots. At this level, the cyclone can cause great damage.

Level 6 – Type 3 Cyclone

At this stage, the cyclone is labelled a major one. As the sustained winds range from 96 to 112 knots, these storms can cause devastating damage.

Level 7 – Type 4 Cyclone

This stage can cause catastrophic damage to the entire ecosystem it meets. The storm is extremely dangerous and the sustained winds reach 113 to 136 knots.

Level 8 – Type 5 Cyclone

The final stage of the cyclone, sustained winds reach 137 knots and are reserved for the most intense and fatal storms.

Explore the Names of Cyclones 

How to stay super safe when a cyclone comes swirling your way?

Explore these 7 tips that can help you keep super safe during cyclones.

1. Stay informed and keep a constant tab on weather updates from credible and verified sources.

2. Familiarise yourself with shelters and evacuation routes and plans designed by your local government.

3. Close all your windows and doors and reinforce them with sturdy materials like plywood.

4. Stock emergencies supplies like food, medical kits, water, non-perishable food, important documents, batteries, and flashlights.

5. Turn off gas, electricity, and water supplies to prevent potential hazards.

6. Charge all devices beforehand and only use them for emergencies.

7. Try to stay calm and only venture out when authorities declare it safe to do so.

Conclusion

Cyclones are powerful forces of nature that cause mass destruction. They are huge air masses that swirl and rise around a low-pressure area. We also learned how the Coriolis effect influences the rotational speed of the cyclone. The regions frequently affected by cyclones in India are West Bengal, Odisha, Andhra Pradesh, and Tamil Nadu. We also learned about different levels and stages of cyclones to be aware of when the first signs occur and take precautionary measures accordingly. 

Now that you have understood about cyclones, share this information with your friends and family. Be the champion of cyclone safety!

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