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Chapter 8 – Winds, Storms and Cyclones

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

When the air moves in a particular direction due to currents, the phenomenon is called winds. Have you ever been to a beach when it is incredibly windy? You must have seen how strong the air current is during the day that your hair and clothes are blown in one particular direction. This happens because a large mass of air is horizontally displaced from the sea towards the beach.

The motion of wind depends on pressure conditions. The wind moves from high pressure to low pressure. Its speed depends on the difference between the pressure of one place from the other.

Have you ever wondered why a flaccid balloon inflates on blowing air into it? Or why you find it difficult to cycle against the direction of the wind. This is because air exerts pressure. In the first case, it causes the walls of the balloon to stretch, and in the second, it applies pressure against the cycle, making it difficult to ride.

Take a ball of crumpled paper, and keep it just inside the mouth of an empty bottle while holding it parallel to the ground. Now, try to blow inside the bottle forcing the ball of paper to go in. You will find it very difficult to make the ball go inside the bottle, no matter how much force you blow with. 

When you blow in the mouth of the bottle, the speed of the air near it is higher. This decreases the pressure at that point. The air pressure is higher inside the bottle than near the mouth. Thus, the air inside the bottle pushes the ball out.

With increased wind speeds, the air pressure reduces, and vice versa.

Take a tube kept in boiling water and stretch a balloon tightly over it. Insert this tube in a beaker that has hot water. Observe what happens to the balloon. Then, place the tube in ice-cold water and observe what happens. You will notice that when the tube was kept in hot water, the balloon was inflated. When it was kept in cold water, the balloon deflated.

This happens because air expands on heating and occupies more space. Thus, warm air is lighter than cold air.

  1. Uneven heating between poles and the equator
    You have already learnt that the sun’s heat is maximum at the equator and nearby areas. The air near the equator gets warm and rises up, creating a low-pressure zone. The cold air from the surrounding areas rushes in to take its place, both the north and the south. The polar regions have colder air as compared to 60-degree latitude areas, and as this air rises up, the winds from polar regions rush in to take their place. In this manner, wind circulation takes place from the polar regions to warmer latitudes.
  2. Uneven heating of land and water and water
    In summer, the land warms up faster near the equator. The temperature on the ground is higher than that on oceans. The air above the land gets heated up and rises, creating a low-pressure area. The winds over the oceans, a high-pressure area, flow towards the land. These are called monsoon winds. These carry water with them and cause rains.

 

In winter, the direction of the winds is reversed,i.e., from land to the ocean.

Storms

Did you know that thunderstorms are so common that there are about 14 million per year, almost 40,000 per day? Mostly thunderstorms develop in hot and humid regions, like India. When the conditions are hot, and the temperature rises, the air becomes hot and rises upwards. It carries water vapour along with it, which condenses to form clouds on reaching high altitudes. When the water droplets get heavy enough, they fall as rain. Lightning and strong winds accompany rainfall.

Cyclones

The term ‘cyclones‘ refers to weather systems in which the winds or large air masses rotate or spiral violently inwards to an area of low atmospheric pressure. In the Northern hemisphere, the circulation pattern is counterclockwise, while in the Southern hemisphere, it is clockwise.

During a thunderstorm, when water vapour changes to water at higher altitudes, it releases heat. This heat warms the surrounding air and creates a low-pressure zone. Because of this, cooler winds rush towards the centre of the storm. As the cycle continues, a large low-pressure area is formed, which is accompanied by high-speed winds. This is a cyclone.

Moving air is called wind. The circulation of wind over the surface of the earth is regulated by uneven heating. This creates a pressure difference, which causes the movement of air.

What are wind, storm and cyclone?
When the air moves in a particular direction due to currents, the phenomenon is called winds.
The term ‘cyclone‘ refers to weather systems in which the winds or large air masses rotate or spiral violently inwards to an area of low atmospheric pressure.
A storm is a meteorological phenomenon that is accompanied by high-speed winds and heavy rain.

What is a cyclone?
The term ‘cyclone‘ refers to weather systems in which the winds or large air masses rotate or spiral violently inwards to an area of low atmospheric pressure.

What is the difference between storm and cyclone?
A storm is a meteorological phenomenon that is accompanied by high-speed winds and heavy rain. Whereas a cyclone is a weather system in which the winds or large air masses rotate or spiral violently inwards to an area of low atmospheric pressure.

How does a thunderstorm become a Cyclone?
During a thunderstorm, when water vapour changes to water at higher altitudes, it releases heat. This heat warms the surrounding air and creates a low-pressure zone. Because of this, cooler winds rush towards the centre of the storm. As the cycle continues, a large low-pressure area is formed, which is accompanied by high-speed winds. This is a cyclone.

What are the four types of winds?
Easterly Prevailing Winds, Westerly Prevailing Winds, Polar Easterlies, and Periodic Winds.

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High School Physics

  • Alternating Current
  • Atoms
  • Communication Systems
  • Current Electricity
  • Dual nature of Radiation and Matter
  • Electric Charges and Fields
  • Electricity
  • Electromagnetic Induction
  • Electromagnetic Waves
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  • Electrons and Photons
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  • Force and Acceleration
  • Force And Laws Of Motion
  • Gravitation
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  • Law of motion
  • Light – Reflection And Refraction
  • Magnetic Effects Of Electric Current
  • Magnetism and Matter
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  • Mechanical properties of Fluids
  • Mechanical properties of Solids
  • Motion
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  • Paths of Heat
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  • Sound
  • Sources Of Energy
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  • Systems of Particles and Rotational motion
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  • Units and Measurement
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High School Chemistry

  • Acids, Bases and Salts
  • Alcohols, Phenols and Ethers
  • Aldehydes, Ketones and Carboxylic Acids
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  • Atomic Structure
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High School Biology

  • Absorption and Movement of Water in Plants
  • Adolescent Issues
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  • Animal Kingdom
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  • Flowering Plants
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High School Math

  • Algebra – Arithmatic Progressions
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  • Algebra – Pair of Linear Equations in Two Variables
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  • Algebra – Principle of Mathematical Induction
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Middle School Science

  • Acids, Bases And Salts
  • Air and Its Constituents
  • Basic Biology
  • Body Movements
  • Carbon and Its Compounds
  • Cell – Structure And Functions
  • Changes Around Us
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  • Fun With Magnets
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  • Stars And The Solar System
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  • Transportation In Animals And Plants
  • Universe
  • Waste-water Story
  • Water: A Precious Resource
  • Weather, Climate And Adaptations Of Animals To Climate
  • Winds, Storms And Cyclones

Middle School Math

  • Addition
  • Area and Its Boundary
  • Boxes and Sketches
  • Data Handling
  • Fun With Numbers
  • Heavy and Light
  • How Many
  • Long And Short
  • Mapping
  • Measurement
  • Money
  • Multiplication and Factors
  • Multiply and Divide
  • Numbers
  • Parts and Wholes
  • Pattern Recognition
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  • Play With Patterns
  • Rupees And Paise
  • Shapes And Angles
  • Shapes And Designs
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  • Similarity
  • Smart Charts
  • Squares
  • Subtraction
  • Tables And Shares
  • Tenths and Hundredths
  • Time
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