What causes it to rain?

At the opposite extreme is a tropical rain shower that has large amounts of water vapor available to it (like the one pictured at the top of this page), and which can rain heavily from even a small cloud with weak updrafts. read more

The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. read more

If there are clouds out and about but no rain, then the cloud lacks enough water vapor to form the precipitation or the cloud doesn't have enough rising motion inside of it. When air masses are warmer, rain usually takes place inside localized clouds featuring harder updrafts. read more

Any time the droplets in clouds grow and come together to form drops that are large enough to create a speed of falling that is greater than the speed at which the cloud is blowing upward, then they head downward, and if they make it down without evaporating, people on the ground experience them as rain or snow. read more

Rain holds an important religious significance in many cultures. The ancient Sumerians believed that rain was the semen of the sky-god An, which fell from the heavens to inseminate his consort, the earth-goddess Ki, causing her to give birth to all the plants of the earth. read more

Rain is responsible for most of the fresh water on Earth and it is essential to life. It is part of the water cycle, the continuous movement of water between the Earth and the atmosphere. In the water cycle, water is evaporated and transpired into the atmosphere. read more