It needs water vapor
in order to form

Clouds.

Clouds are created when water vapor, an invisible gas, turns into liquid water droplets. These water droplets form on tiny particles, like dust, that are floating in the air. ... That means some of the liquid water in the towel or bowl changed into an invisible gas called water vapor and drifted away into the atmosphere.

I mean i don't really know tbh ;-;
Maybe condensation??? but i feel like that would be too easy.
Without water vapor, there would be no clouds or rain or snow, since all of these require it in order to form and
Condensation is the process by which water vapor in the air is changed into liquid water. As condensation occurs and liquid water forms from the vapor, the water molecules become more organized and heat is released into the atmosphere as a result.

i don't wanna give a distinct answer because i could very possibly be wrong but i hope this helps in some way!

Because the carnivores keep the herbivore population in check 

Yes yes yes very good