Is Mesopause a Noun?

Mesopause is a noun. A noun is a type of word the meaning of which determines reality.

What is meant by mesopause?

: the upper boundary of the mesosphere where the temperature of the atmosphere reaches its lowest point.

What do you mean by stratosphere?

The stratosphere is a layer of Earth's atmosphere. It is the second layer of the atmosphere as you go upward. ... Ozone, an unusual type of oxygen molecule that is relatively abundant in the stratosphere, heats this layer as it absorbs energy from incoming ultraviolet radiation from the Sun.