Clouds form when moisture (water vapor) in the air is cooled either to condensation or to "sublimation", which is the formation of ice crystals from the water vapor rather than raindrops.
(when moisture (water vapor) in the air; is cooled; T:Clouds form) (sublimation; is; the formation of ice crystals from the water)
when moisture (water vapor) in the air sublimation
is cooled is
T:Clouds form
the formation of ice crystals from the water