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๐ฌ Think about it
A cyclone can push a wall of seawater 12 metres high onto the shore and take years to recover from. Yet at its very centre is a patch of calm called the eye. How does warm ocean water spin up into such a giant, and why is its heart so still? Let's see.
How does a cyclone form?
- Warm ocean water heats the moist air above it, which rises.
- Its water vapour condenses into raindrops, releasing heat that warms the air further.
- The air rises even more, creating very low pressure; surrounding air rushes in and rises too.
- The Earth's rotation makes the moving air spin, forming a cyclone.
How a Cyclone Forms
Warm moist air rises
Over warm ocean; vapour condenses and releases heat
↓
Very low pressure
Air rises more; surrounding air rushes in and rises
↓
Earth's rotation makes the system spin → a cyclone
What is the eye of a cyclone?
- The eye is the region of lowest pressure at the centre of the cyclone.
- At the eye, the wind is calm.
- The region around the eye has strong winds and heavy rainfall.
- Once a cyclone reaches land, its moist-air supply is cut off and it slowly weakens.
How destructive are cyclones, and how do we stay safe?
- Cyclones can be extremely destructive — the Amphan cyclone (2020) had peak winds of 270 km/h.
- They push seawater into a wall 3–12 m high that floods coasts, contaminates water and damages farmland.
- Stay updated on alerts from the India Meteorological Department (IMD); satellites help track cyclones.
- Keep an emergency kit ready and move to a cyclone shelter during a cyclone.
Let us wrap up: the steps from warm air to a cyclone
- Warm air rises, creating a low-pressure area; cool air rushes in to take its place.
- The rising air cools and its water vapour condenses to form clouds.
- Bigger drops fall as rain, hail or snow; up-and-down winds build positive and negative charges.
- When the charges meet, lightning occurs; under certain conditions, storms grow into cyclones.
Let Us Wrap Up
Warm air rises
Low pressure forms; cool air rushes in
↓
Clouds and rain
Vapour condenses to clouds; big drops fall as rain
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Charges and lightning
Up-and-down winds build charges; meeting charges make lightning
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Under certain conditions, storms develop into cyclones
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Test Yourself
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Where do cyclones form?
View Answer
Over warm ocean waters. -
What makes a cyclone spin?
View Answer
The Earth's rotation makes the rushing air spin. -
What is the eye of a cyclone like?
View Answer
It is the calm, lowest-pressure region at the centre. -
Why does a cyclone weaken over land?
View Answer
Its supply of warm moist air from the ocean is cut off. -
Which department monitors cyclones in India?
View Answer
The India Meteorological Department (IMD).
Important Definitions
- Cyclone — A large spinning system of clouds, winds and rain formed over warm ocean waters around a very low-pressure centre.
- Eye of the cyclone — The calm, lowest-pressure region at the centre of a cyclone.
๐ NCERT Question 2 — State whether the following statements
True or False: air flows high to low pressure; liquids press only at the bottom; the eye is stormy; a car is safer in a thunderstorm.
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๐ NCERT Question 8 — Explain how a storm becomes
Explain how a storm becomes a cyclone.
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