The heating and cooling of the atmosphere is a regular process. All objects which get heated up by insolation get cooled down after some time.
The earth being a part of the solar system also gets heated up by insolation from the sun. This warming process does not remain uniform, there are different ways in which this heating occurs.
The air in contact with the land gets heated slowly and the upper layers in contact with the lower layers also get heated. This process is called conduction.
Conduction takes place when two bodies of unequal temperature are in contact with one another, there is a flow of energy from the warmer to cooler body. The transfer of heat continues until both the bodies attain the same temperature or the contact is broken. Conduction is important in heating the lower layers of the atmosphere.
The air in contact with the earth rises vertically on heating in the form of currents and further transmits the heat of the atmosphere. This process of vertical heating of the atmosphere is known as convection.
In middle latitudes, most of diurnal (day and night) variation in daily weather are caused by advection alone. In tropical regions particularly in northern India during summer season local winds called ‘loo’ is the outcome of advection process.
