How is doldrum pressure formed?

The equatorial area is a region of high temperature. Due to intense heating, the atmosphere heats up, expands and becomes lighter. Hence, the air starts rising vertically, causing low pressure on the ground. The horizontal movement of wind in this belt is very feeble. It is, therefore, a calm belt, also known as doldrums.

Doldrum Pressure, Equatorial Area, Atmosphere Heats, Horizontal Movement, High Temperature, How is doldrum pressure formed