Ans: The general circulation of the atmosphere on Earth is mostly driven by the Sun. The surface of land gets heated due to solar radiation. The land can absorb only some amount of the radiation and the remaining it reflects. This reflected heat warms up the air above it and makes it less dense. Because of less density as compared to the air above it, the warm air rises and creates a low pressure area in its previous place. The cold air surrounding such a region is attracted towards this low pressure area and an air current known as the wind is generated in that direction. On the other hand, the warm air travels up high in the troposphere and starts travelling in the direction of the poles. While travelling in that direction over time, it cools and then drops down towards the land after reaching a certain latitude. As the air reaches the land, after some time it again starts its journey towards the low pressure area which consists of warm heat because of solar radiation and the cyclic journey starts. Thus, this concept underlies the major mechanism of any of the general circulation of the atmosphere.