Winds, Storms and Cyclones - Class 7 Science Chapter 8 Notes

Class 7 Science Chapter 8 - Winds Storms and Cyclones notes provided here are useful for preparation of class 7 CREST Science Olympiad (CSO) and similar competitions. It is very important for the students to provide equal attention in class 7 to all the topics and focus on developing their fundamental concepts on each topic. To make it easier for students to strengthen their preparation, we created Winds Storms and Cyclones class 7 notes in a clear, understandable and condensed style that enables students to swiftly learn all the challenging material before the exam. The notes include in detail information about the topic to help students. Wind, Storm and Cyclone pdf is also available here to download for free.

Winds Storms and Cyclones class 7 pdf for notes is also available for free download that students can refer to.

Class 7 Science Chapter 8 - Winds Storms and Cyclones Notes

Air: Air is a mixture of gases.

Wind: Moving air is called wind.

Air exerts pressure: Many examples can help you understand how air exerts pressure. These are what they are:

1. The tube of a bicycle gets inflated when air is filled in it. This happens because air exerts pressure. It is difficult to move the bicycle against the direction of wind. Similarly, a sailor finds it challenging to sail his boat against the wind. This happens because air exerts pressure.
2. When boiled water is filled in a tin can and its mouth is closed with the lid; followed by cold water being poured over it, it gets distorted. This happens because air inside the can gets condensed and creates low pressure. The higher pressure from outside distorts the shape of the can.
3. You can fly a kite because air exerts pressure from the rear portion of the kite.
4. An airplane can fly because air exerts pressure.
5. Birds can fly because air exerts pressure.
6. High-speed wind creates areas of low air pressure.
7. Thatched roof is blown off because of high-speed wind. This happens because high-speed wind creates an area of low pressure. As a result, the thatched roof is sucked up and finally gets blown away. Thus, an increase in wind speed is associated with a decrease in air pressure.

Movement of air
Air moves from a high-pressure zone to a low-pressure zone of air. To fill the vacant space, air from the high-pressure region rushes toward the low-pressure region. Thus, greater the pressure difference greater will be the speed of the wind and vice-versa.

Cause of Wind Movement

Pressure difference in the air is caused by differential heating. Warm air rises up because it becomes lighter. This creates an area of low pressure below the rising atmosphere. Cooler air from around swiftly fills the area of low pressure. That is how the wind movement is created on the earth. Thus, a pressure difference caused by the differential heating of the air produces wind movement.

Movement of Air Because of Uneven Heating on Earth

Movement of Air in Equatorial Region

The Equatorial region gets the highest amount of sunshine throughout the year. As a result, the air close to the equatorial zone warms up. An area of low pressure is created when the warm air rises. The cooler air; from the higher latitudes; rushes towards the equator to fill the gap. This results in the wind movement from tropical zones towards the equator. Similar factors contribute to wind migration in various places on the planet.

Movement of Air Because of Uneven Heating of Land and Water

Sea Breeze

In coastal areas, the land warms up faster than the ocean surface. Low pressure develops close to the ground when warm air from the land rises. Cooler air from the ocean's surface fills the low-pressure area. Thus, resulting in the sea breeze.

Land Breeze

During the night, the land cools down faster than the ocean surface. The warmer air from the ocean surface rises up and creates an area of low pressure near the surface. This is filled in by cooler air from the land. This gives rise to the land breeze.

Monsoon

Monsoon or monsoon wind refers to the summertime movement of humid air from the ocean towards land. The word Monsoon came from the Arabic word ‘mausim’, which means weather. The normal weather on the Indian Peninsula during the rainy season had long been referred to as the "monsoon."

Nowadays, the term ‘Monsoon’ is also being used to describe the similar climate in other parts of the world. Water vapour carried by monsoon winds cools and then falls as rain over the land. In India, the harvest depends on the monsoon wind because it is the major factor towards bringing rainfall to India.

Thunderstorm

Many times, rain is associated with lightning. Rain with lightning is called a thunderstorm. This happens mostly in the summer. Thunderstorm occurs frequently in hot and humid tropical areas, such as India.

In summer, the air rises up along with a lot of moisture. Water vapour begins to descend as water droplets after reaching a particular height and cooling down. The rapid movement of water droplets in the air generates electricity in the clouds. Lighting and sound are examples of how this occurs. This is known as a thunderstorm.

Cyclone

Fast-moving air towards a centre; usually with heavy rain; is known as a cyclone. Wind direction, wind speed, humidity and temperature together create cyclones.

Heat is released when cloud water vapour cools down. The air around the clouds warms up due to this heat. A low-pressure area is produced as the warm air rises. Cooler air from the surroundings quickly fills in this low-pressure area. As a result, a system is formed with a very low-pressure centre and wind blowing all around it. Cyclones are created when the wind from the surroundings flows in a circular motion toward the centre.
The centre of the cyclone is called ‘eye’. A cyclone may be 10 to 15 km high. It is a rotating mass of air. The diameter of the eye may vary from 10 to 30 km. Eye of a cyclone is a calm area, but around the eye, air may move at high speeds such as 150 to 250 km/h.
The destruction caused by cyclones: A strong cyclone can be very destructive.

Since cyclone is accompanied by high-speed wind, they can damage houses, telephone poles, and electric poles and uproot trees.

The seawater may be pushed toward the seashore by the cyclone's strong winds in the form of large waves. High waves have the potential to destroy homes and drive water into low-lying areas, which could result in casualties and damage to property.

Being the area of very low pressure, the eye of the cyclone lifts water in the centre. Water levels could rise by 3 to 15 metres as a result of this. This appears like a water wall. This water wall; when pushed towards the seashore; can inundate a large area, which can cause the loss of life and property.

In India, the eastern coast is more vulnerable to cyclones than the western coast, both in terms of their frequency and strength.

Different nations have different names for cyclones. In the American continent, a cyclone is referred to as a HURRICANE. In the Philippines and Japan, it is referred to as TYPHOON.

Tornadoes

Tornadoes are very fast-moving dark clouds in the shape of a funnel. The speed of violent tornadoes may be up to 300 km/h. Tornadoes are as destructive as cyclones. Tornadoes may form within cyclones.

Anemometer

An instrument which measures the speed of the wind.

Effective Safety Measures

1. Safety services towards cyclones and other disasters by Government and other agencies:

1. Cyclone forecast and warning services: With the advances in technology, cyclones can be forecast about 24 to 48 hours in advance. Satellites and computers enable this to happen. A cyclone warning is predicted almost every half-hour when a cyclone is closer to the coastline.
2. Rapid communication to the Government and concerned people: The government and the people are swiftly informed about the cyclone so that appropriate safety precautions and rescue efforts can be taken.
   > Building cyclone shelters in the cyclone-prone area.
   > Shifting the crowd quickly to a safer place.

2. Action on the part of people:

1. Occasionally, pay attention to warning broadcasts.
2. Stock up on the necessary food and medications in case of a cyclone warning.
3. If possible, move to a safer place.
4. Fishermen should not venture into the sea during a cyclone warning.
5. Cooperate with others in the community.
6. Help the rescue team.

Conclusion

Students should hopefully leave with a general understanding of the chapter - Winds Storms and Cyclones. It includes in detailed explanation of each topic along with various examples for the students to understand the concept more clearly and precisely. The given content is created in accordance with the current syllabus and is updated annually to reflect changes made by the central boards. Enjoy reading Wind, Storms and Cyclones class 7 pdf notes.

Notes are just text if we don’t test the learning later. To improve performance and move forward in the right direction, students must test their knowledge. CREST Olympiads through its exams provides a platform to test and advance understanding of concepts. We recommend class 7 students to appear for CREST Science Olympiad to test their understanding of Science concepts. To register, visit CREST Science Olympiad registration link.

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We look forward to continuing to provide revision notes for each lesson for class 7. As mentioned above Class 7 Science Chapter 8 pdf is available to download for free. Students are advised to download the pdf by clicking on the below link.

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