You might have flown through clouds in an aircraft or been high up on a mountain where clouds swirled all about you. These clouds are nothing but an accumulation of mist. There is always water vapor in the air and during summer there is more of this vapor as the temperature is higher. When there is so much water vapor in the air, just a small reduction in temperature will make the vapor condense and we say the air is saturated.
It takes only a slight drop in temperature to make water vapor condense in saturated air. So when saturated warm air rises to an altitude where the temperature is lower, condensation takes place and we have a cloud. The molecules of water have come together to form countless little droplets.
What happens if all these water droplets in a cloud meet a mass of warm air? They evaporate and the cloud disappears! That is why clouds are constantly changing shape. The water in them is changing back and forth from vapor to liquid.
The droplets of water in a cloud have weight, so gravity gradually pulls them down and they sink lower and lower. As most of them fall, they reach a warmer layer of air, and this warmer air causes them to evaporate. So here we have clouds that don’t produce rain. They evaporate before the drops can reach the earth as rain.
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