Sun’s rays fall vertically to the north of the equator during certain months due to the tilt of the earth’s axis. This leads to an increase in temperature along the region through which Tropic of Cancer passes. The pressure belts also shift slightly northwards in accordance with this.
The south east trade winds cross the equator and move towards the north. As the trade winds cross the equator, they get deflected and transform into south west monsoon winds under the influence of the Coriolis effect. The low pressure formed over the land due to the intense day temperature attracts these sea winds and further contributes to the formation of south west monsoon winds.
