You must have seen the whistle of cooker releases the sudden flow of air. Why does it happen? As we have learnt previously that when temperature of air increases, it tries to occupy more space due to increase in its pressure, for this the highly compressed air exerts pressure on the wall and lid of cooker. When this pressure is more than the weight of that whistle, whistle lifted up and releases the air through small hole in it, and air flows with high speed. Thus air exerts pressure on all objects in its path.
Consider one more example, that you are enjoying sea shores on the beach and suddenly a flow of cold air from surface of ocean travels towards beach and you enjoy the joystick sensation of that colder air. The colder air reaches to you due to formation of “breeze “known as Sea breeze, which is another example of moving air.
The moving air with certain speed is known as Wind. The movement of air i.e. Winds is caused to temperature difference at every point on earth.
Temperature and pressure at every point on the earth is not same, instead it’s different for all locations on the earth. As a result of this, the air also flows with different pressures and different speeds on all over the earth. Wind speed decides the conditions of weather (climate) on the surface of earth.
Winds from surface of oceans carries water vapours due to evaporation by heat from sun, and comes back as a rain when temperature of surrounding decreases.
There are some important types of winds viz.
- Planetary Winds 2. Trade Winds 3. Local winds
Some other types of winds are distinguished due to its direction of flow as Westerlies and Easterlies, which moves from poles to equator of earth at different latitudes. We know that the equator of earth is close to sun, so receives more heat energy from sun, which increases the temperature on equator. But the polar region of earth is far from sun, hence become colder than equator. This makes Wind to blow at different speeds from equator to poles but not in straight line from North Pole to South Pole or vice versa, instead it goes at different angles.
Wind flow of the speed around 20 miles per hour is always around us, which creates the sensation of breezes around us. But when a wind blows with high speed, it becomes disastrous which creates Cyclones, Thunderstorms etc. We will learn about the disastrous impacts of wind in next part.
Q. What do you mean by Wind?
Ans: The moving air due is known as wind.
Q. What is the factor responsible to move air?
Ans: Different temperature at different point makes air to flow.
Q. What are types of winds?
Ans: 1. Planetary Winds 2. Trade Winds 3. Local winds
Q. How Sea breezes are formed?
Ans: Hot air from the land (beach) flows towards the ocean and cold air above the ocean surface flows towards land, which forms a flow of cold airon beach known as Sea breeze.