Black or dark gray shapeless masses of thick vapor, formed at middle levels or very near to the surface of the earth that are extremely dense and opaque to the rays of the sun are called _____?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Nimbus clouds
Clouds are named by their form and height. Nimbus clouds are the black or dark grey rain clouds that form at middle levels or very close to the surface of the earth. They are shapeless masses of thick vapour, so dense that the rays of the sun cannot pass through them, and at times they hang so low that they seem to touch the ground.
Why the other options are incorrect
Option (1) Stratus clouds — Incorrect. These are layered clouds spread as sheets over large parts of the sky, not shapeless dark masses.
Option (3) Cirrus clouds — Incorrect. These are thin, white, feathery clouds at high altitudes (8,000-12,000 m), far from the surface.
Option (4) Cumulus clouds — Incorrect. These look like heaps of cotton wool, scattered in patches with flat bases.