We all know that air is the mixture of gases like nitrogen, oxygen, nitrogen, dust particles, water vapors. When the air is in motion we call it the wind.
Let us study how the wind blows?
When an area of the earth gets heated by the rays of sun then the air of that area of earth also gets heated. Because of this heating the air gets expand and thus it becomes lighter or its density gets decrease. The hot air goes up in the atmosphere as it becomes lighter and then the atmospheric pressure of that area gets decrease. In such condition, air rushes to that area from the high pressure cod areas to restore the balance. This movement of air is known as blowing of wind. During the day the earth of the areas near the sea becomes hot.
Because of this the air of this area becomes lighter and goes up in the atmosphere. Then from the sea the cold air blows towards the land to fill up the empty space. Whereas, at night the earth becomes colder than the sea water and the air moves from the land towards the sea. The regions surrounding the equator are very hot and the hot air from these areas constantly moves upward. This hot air flows out to the south and north poles. The directions of wind are very much effected by the rotation of earth on its axis. The rotation of earth makes all the winds in the northern hemisphere blow towards the right, whereas the winds in the southern hemisphere towards left. The direction of winds is also influenced by mountains. They get in the way the winds and then change their directions.