Question

Why is the name ‘doldrums’ used for equatorial pressure belts?

Answer 1

Hint: There are numerous pressure belts spread across the surface of the earth. These are either high-pressure belts or low-pressure belts. Owing to the Geodic shape of planet earth, we experience that the earth’s surface gets heated unevenly.

Complete Answer:
The equator is a parallel of latitude 0 degrees. The hot sun rays fall directly on the region around the equator. The degree of heat or warmness is very intense throughout the year. The hotter the air, the lighter it is. So, the air in and around the equator being light rises and results in the creation of a low-pressure area. On the contrary, the opposite mechanism holds true thereby forming high-pressure areas. The earth’s surface is broadly divided roughly into seven pressure zones. They are- the Equatorial Low, the two Subtropical highs, the two Subpolar lows, and the two Polar highs. A broad area where we get to see the convergence of northeast and southeast trade winds is a trough of low pressure in the latitudes near the equator. In geographic terms, it is called ‘ Inter-Tropical Convergence Zone’. This region of low pressure is a total area of calm. No breeze flows in this belt. Hence, the term ‘doldrums’ is used to describe the equatorial pressure belts.

Note: The latitudinal extent of the equatorial pressure belt is up to five degrees both north and south of the equator. Upon intense heating, the air in this extent rises as convection currents after expanding. As a result, a trough of low pressure develops.