Both wind and earth are not stationary, i.e., they keep on moving. The change in the direction of wind is basically due to the rotation of the earth.

Anything which is lighter in weight as compared to the other will rise up. The smoke produced from the burning process is hotter and lighter in weight. That is why it can always be seen rising up in the air.

Burning of a candle, fuel or a cigarette does not show that air exerts pressure. On the other hand, pressure exerted by air can be felt in riding a bicycle, flying a kite, rowing a boat and opening a soft drink bottle. 

Wind always moves from a region of higher pressure to lower pressure. When it leaves a place of high pressure, a low pressure is created in that region. Therefore, an increased wind speed is always accompanied by reduced air pressure.

Winds are the air currents which are generated due to the uneven heating of the earth’s surface. The uneven heating of the earth that causes the movement of air is called atmospheric convection.

Gases always move or flow from a region of higher pressure to lower pressure. As air is also a mixture of gases, it also moves in the same direction.

Air expands on heating. The tube of a bicycle in summers expands due to the expansion of air inside it. This happens due to an increase in temperature in summers and hence, causes more punctures in a bicycle tube.

Air is always colder in the polar region than latitudes. Movement of hot air from latitudes to the polar region or cold air from the polar region to latitudes can take place, but the movement of hot air from the polar region to the equator is not possible.

A thunderstorm creates lightning and sound. Therefore, one should never lie on the ground, never use an umbrella with a metal rod and never hide oneself in a swimming pool or any conducting material. One may take shelter under a tree in an open field.

The eastern coastline of India is the most vulnerable to cyclonic storms.The western coastline of India is less vulnerable to cyclonic storms, both in terms of intensity and frequency of cyclones.

The centre of a cyclone is a calm area called the eye of storm. Its diameter is about 10 – 30 km. This region is free of clouds and has light winds. 

During the formation of a cyclone, many events take place. There occurs the formation of a low pressure system at the centre with winds at a very high speed revolving around it. This central region of low pressure is known as the eye of the cyclone.

The swift movement of falling water droplets along with rising air creates lightning and sound, which is known as thunderstorm.

The centre of a cyclone is a calm area called the eye of the storm. Its diameter is about 10-30 km. This region is free of clouds and has light winds. The speed of wind in this region is 150 – 250 km/h.

Cyclones with violent height of 10 – 15 km can cause floods, damage to communication systems and cause harm to life. They never result in enhancing soil fertility.