Question

What is doledrums?where does it exists in the earth zones

Answer 1

doldrums is area which receives direct rays of sun and remain hot throughout year.it lies from 5°n to 5°s .

Answer 2

here is your answer

in equatorial low pressure( 5°N to 5°S ) belt the sun's rays are vertical throughout the year. As a result the temperature in the equatorial region is very high. the air near the surface gets heated and expands. hot air is light so it rises resulting in a low pressure belt in this region.
the air in this belt rises up to form convention currents and there is no horizontal movement of air. it is an area of calm and therefore is also known as the Doldrums.

hope it helps you