Convection--: It is the process by which heat is transmitted through a substance from one point to another due t_Q the bodily motion of the heated praticles of the substance.

(i) Trade winds --: The surface of the earth near the equator is heated by the sun. The are in contact with the surface of the earth becomes warmer and rises upwards. The are from the  colder polar regions rushes in towards the equatorial regions, thus producing northward wind in northern hemisphere and southward wind in southern hemisphere. Due to the rotation of the earth about its axis from west to east, the actual direction of the wind in the northern hemisphere is north -east and in the southern hemisphere, south-west. These winds are called trade winds.

(ii) Land and Sea Breezes --: Water has a high Specific heat.

Therefore, it is less readily heated by the sun than land. In other words, during the day the and land is heated by the sun to a higher temperature than water in the  sea. Air over the land is therefore heated, expands and rises while the cooler air from the sea blows towards land to take its place which constitutes the sea breeze.

At night the land is no longer heated by the sun. It therefore, cools, But land cools much faster than water due to high specific heat capacity of water. By comparison the sea is much warmer than land at night. So at night a current of air blows from the colder land to the warmer sea. This constitutes the land breeze.

Monsoons--: In Summer, the sun is in the Tropic of Cancer. During this time large parts of the earth situated in Central Asia are at a higher temperature than the surroundings oceans. Consequently, winds blow from the ocean to the land carrying moisture with hem. These winds cause widespread rains in India after they strike the mountain ranges.

In Winter, the sun is in the Tropic of Capricorn. During this time the land in the Central Asia is slightly cooler than the sea. Consequently, winds blow from the land to the sea. These winds take up moisture as they pass over the Bay of Bengal and cause rainfall in the coastal such as in Madras. These winds which bring rain are called monsoons.