What is A Cyclone and What are its Different Stages?


While Mother Nature and her wrath can often be devastating and mostly unpredictable, cyclones may provide a little bit of a head’s up. Per year, about 85 storms form over warm tropical oceans across the globe. 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 considered one of the most active cyclone basins in the world. Affected states 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, especially during pre and post-monsoon periods. States like Kerala and Karnataka are states affected by these cyclones.

What is a Cyclone?

A cyclone is an atmospheric system marked by low pressure at the center and circulating winds that move in spiral movements inwards. The rotation can be extremely powerful and can cause winds, rainfall, harsh storms, and also 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.

How do Cyclones Occur?

For cyclones to form, many elements 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 step in. As the earth is continuously turning, the air doesn’t 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.
As a cyclone becomes bigger and intensifies, it undergoes many stages, which we will now discuss in brief.

The Different Stages of a Cyclone:

As a cyclone develops, it typically goes through 8 stages:

Stage 1 – Tropical Disturbance

The first stage of a cyclone begins as a cluster of thunderstorms that form over warm ocean waters. There is no discernible circulation at this stage.

Stage 2 – Tropical Depression

In this stage, there is a clear circulation pattern with sustained winds of up to 61.15 kilometers 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 kilometers per hour and one nautical mile the same as 1.852 kilometers.

Stage 3 – Tropical Storm

As the sustained winds reach 34 to 63 knots, the process is referred to as a tropical storm and is given a name at this point. 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.

Stage 4 – Category 1 Cyclone

When the sustained winds reach 64 to 82 knots, it is classified as a Category 1 cyclone in the Southwest Indian Ocean and South Pacific. This is when damage to trees and mobile homes occur and can also lead to minor flooding cases in the coastal areas. 

Stage 5 – Category 2 Cyclone

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

Stage 6 – Category 3 Cyclone

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

Stage 7 – Category 4 Cyclone

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

Stage 8 – Category 5 Cyclone

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

How to Stay Protected During a Cyclone:

Follow these tips to ensure that you are doing your best to stay safe during a cyclone:

  • Stay informed and keep a constant tab on weather updates from credible and verified sources.
  • Familiarize yourself with shelters and evacuation routes and plans designed by your local government.
  • Close all your windows and doors and reinforce them with sturdy materials like plywood.
  • Stock emergencies supplies like food, medical kits, water, non-perishable food, important documents, batteries, and flashlights.
  • Turn off gas, electricity, and water supplies to prevent potential hazards.
  • Charge all devices beforehand and only use them for emergencies.
  • Try to stay calm and only venture out when authorities declare it safe to do so.

At EuroKids, we encourage scientific minds and those who show a special interest in nature. Our extensive curriculum is especially designed to stimulate young minds and transform them into brilliant leaders of tomorrow. So, whether it’s learning about cyclones or learning how to stay safe during tough times, we ensure that we cover everything your child needs to know. As India’s leading pre-school network, we’re privileged to have nurtured over 7,00,000+ children in over 1400 pre-schools across 350+ cities. Will we be seeing your child in one of our schools next?