Have you ever flown through clouds in an aircraft, or perhaps been high up on a mountain where the clouds swirled act about you? Then you must have gained a fairly good idea of what a cloud is: just an accumulation of mist.

As you know, there is always water vapor in the air. During the summer there is more of this vapor in the air because the temperature is higher. When there is so much water vapor in the air that just a small reduction in temperature will make the vapor condense Form tiny droplets of watery, we say the air is saturated.