Chapter 8 Winds Storms and Cyclones Class 7 Notes

These Winds Storms and Cyclones Class 7 Notes will help you understand the science behind the formation of thunderstorms and cyclones. We will understand how the wind moves, how thunderstorms and cyclones occur, what damages are caused by these natural phenomena, and what precautions one should take.

Winds Storms and Cyclones Class 7 Notes Overview

  • How Air exerts pressure
  • Expansion of Air on heating
  • Winds
  • Generation of Winds
  • Thunderstorms and Cyclones
  • Damages caused by Thunderstorms and cyclones
  • Precautions and Safety Measures

Important Points about Air

It is also important to know some of the important terms related to Winds Storms and Cyclones before we dive into these natural phenomena.

Air expands on heating

When air is heated, it expands and occupies more space, and becomes lighter. Here are a few examples-

  • Hot air balloon: The balloon is filled with cool air, and when it is heated, the air inside the balloon heats up, expands, and becomes less dense than the surrounding air. This causes the balloon to rise into the sky.
  • Popcorn: On heating popcorn kernels, the air inside the kernel gets very hot and expands rapidly. This causes the kernel to burst open and turn into fluffy popcorn.

Since the hot air on heating expands and becomes lighter, it rises up. As the hot air rises, its place is occupied by heavy cold air.

Also Read: Sea Breeze and Land Breeze

Air Exerts Pressure

The air around us exerts pressure and this can be seen in many activities such as-

  • Blowing up a Balloon: When you blow up a balloon, you are adding air to the inside of the balloon. The air inside the balloon creates pressure that pushes against the walls of the balloon, causing it to expand and eventually become firm.
  • Inflating a tire: When you inflate a tire, you are adding air to the inside of the tire. The air inside the tire creates pressure that pushes against the walls of the tire, causing it to expand and become firm. This firmness allows the tire to roll smoothly and carry weight.

What is Wind?

It is the natural movement of air (a mixture of gases) in the atmosphere due to differences in temperature and pressure. The air moves from a high-region pressure to a low-pressure region.

What is Air?

It is a mixture of different gases such as Nitrogen, oxygen, carbon di oxide, etc.

What is Atmosphere?

It can be defined as the blanket of air that surrounds the earth and protects us from UV rays,

It extends to hundred of kilometers.

What is Atmospheric Pressure?

The pressure exerted by the atmosphere on the earth surface due to the weight of air above the earth surface.

Barometer is a device that helps us measure the atmospheric pressure.

Generation of Wind Currents

These differences in air pressure are caused by a number of factors, including uneven heating of the Earth’s surface by the sun, the Earth’s rotation, and the presence of high- and low-pressure systems.

Generation of Wind due to Uneven Heating

Uneven heating between the equator and poles

This causes the north-south winds.

Uneven heating of land and water

This causes monsoon winds on Earth which bring rainfall.


A thunderstorm is a type of weather that happens when there is lightning, thunder, and rain. It usually happens in warm and humid regions. It can be dangerous also because of the lightning.

Thunderstorms are caused by warm, moist air rising and colliding with cooler air, which can create clouds and precipitation. Lightning is created by the buildup of electrical charges in the atmosphere. Thunder is the sound created by lightning.


A cyclone is a big storm that happens over the ocean. It can bring lots of rain and really strong winds that can knock down trees and buildings.

  • Cyclones are called typhoons in Japan and the Philippines, and Hurricanes in the American continent.

Damages caused by Thunderstorms and Cyclones

  • Injury or loss of life
  • Property damage
  • Flood
  • Soil Erosion
  • Water pollution
  • Power Outages

Safety Measures

Here is the list of precautions or safety measures we can take to minimize the loss.

  • Stay indoors: If you hear thunder or see lightning, it’s best to stay indoors or seek shelter in a sturdy building. Avoid taking shelter in small, isolated structures like trees or picnic shelters.
  • Keep away from windows: Strong winds and debris can break windows, so it’s best to stay away from them during a storm.
    Stay away from water: Avoid swimming, boating, or being near bodies of water during a thunderstorm or cyclone, as these can be dangerous and increase the risk of lightning strikes.
  • Have an emergency kit: Make sure to have an emergency kit that includes items like a flashlight, battery-operated radio, extra batteries, and a first aid kit. Keep the kit in a safe, accessible place.
  • Follow evacuation orders: If authorities issue an evacuation order, it’s important to follow their instructions and evacuate immediately.
    Stay informed: Listen to local weather reports and stay informed about the storm’s progress. Follow any advice or warnings issued by local authorities.

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