Fill in the blanks.

(i) Air around us exerts __________ .


(ii) The moving air is called _________ .


(iii) The main cause of wind movement is uneven ___________ on the earth.


(iv) High speed wind can cause cyclone in regions of ___________ pressure.

(i). Pressure (Atmospheric pressure)

We know that particles in the air keep on moving and they never stop the same case as in liquids , The moving particles of air exerts pressure on us and everything , if we go into space where there is no air at all then our body will burst out because there is no pressure, so air has pressure that is why they use special suits.


ADDITIONAL INFORMATION – If we go deep inside a sea we will observe a large amount of pressure which is enough to squeeze our body to death that is why they use special suits.


(ii). Wind


Wind is a more scientific term used instead of air because we generally use air to mention about breathing and wind means moving air which can cause tornadoes, cyclones and cools the environment etc. Wind is generally used to study about these phenomena.


(iii). Heating


Pressure depends upon temperature, by this law, we can say that whenever there is a change in temperature or heat at one place the air at that place there is a change in pressure of the gas and to keep the balance in nature air from other places reach the place of change of temperature as winds.


For e.g., If there is a rise in temperature at one place the air will accept heat and expand due to which it will have low pressure, Hence air from other places having a temperature more than this place will reach this place to maintain balance.


(iv). Low pressure


The mechanism of formation of cyclone includes the warming up of water vapour and releasing heat to the atmosphere where air traps this heat and expands creating low pressure area and this cycle continues until there are high speed winds flowing in the low pressure area.



10