Question

why does water vapour consist when it reaches high up in the atmosphere​

Answer 1

Much of the atmosphere is quite cold because sunlight passes through it without getting absorbed much. So, the ground gets hots and water, evaporates when the vapour goes up it reaches coldest parts in the atmosphere and condenses.

Answer 2

Answer:

The main place the water gets heat is down at the Earth's surface, not up in the sky. Much of the upper atmosphere is quite cold because sunlight passes through it without getting absorbed much. ... So the ground gets hot, and water evaporates. When the vapor goes up it reaches colder parts of the atmosphere and condenses