Cloud Formation

A cloud contains millions of water droplets. Clouds form as warm moist air rises and cools. Clouds are divided up into 3 general categories: low (cloud base below 6500 feet), middle (base between 6500 and 23,000 feet) and high clouds (base above 23,000 feet). Low clouds are rain producers. High clouds are often associated with fair weather and could hint at changing weather.

There are 4 main types of clouds: stratus, cumulus, cirrus and cumulonimbus. Stratus clouds are typically low and flat and are often dark. They sometimes produce light rain or light snow. If the cloud is near or on the ground it is known as fog. Cumulus clouds look like puffy cotton balls or cauliflower. They are not flat like stratus clouds. Cumulus clouds grow vertically upward and can at times get very tall. Cumulous clouds are often associated with fair weather, but as they grow higher, they can produce rain. If a cumulus cloud grows tall enough to produce heavy rain and lightning, it is then called a cumulonimbus cloud. Cumulonimbus clouds can extend to around 60,000 feet into the atmosphere. They produce very heavy rain, lightning, and sometimes hail and tornadoes. Cirrus clouds are high clouds that often look thin and wispy. They are made completely of ice. Since light can often shine partially through cirrus clouds, these are the clouds that produce a halo around the sun or moon.

Clouds form when a large bubble of air is heated at the surface. That bubble is made of water vapor (water in a gaseous state). Once that bubble becomes warmer than the air around it, it then is less lighter. At some point, the air bubble is light enough to rise through the atmosphere. As the bubble rises, it encounters cooler air around it (the atmosphere generally cools as you travel higher) and the air in the bubble is then forced to cool as well. Once the air bubble cools the water vapor condenses into water drops. These water drops form the visible cloud. This is the same process that occurs when you see water droplets on the cover of a boiling pot of water. It is also the process that causes your warm breath to fog up a window.

Clouds are vital to the water cycle, and to all life on the Earth. Clouds pick up moisture from oceans and lakes and then drop moisture on other areas.

Questions:

How does invisible moisture become a cloud?

Cirrus clouds produce rain. T/F

Cumulonimbus clouds are thunderstorms. T/F

Fog is a form of stratus cloud. T/F

Cumulous clouds never produce rain. T/F

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