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Anatomy of a Cloud
The white or gray color of clouds is actually the light reflected by tons of little droplets of water and crystals of ice that are so small, they are able to stay in the atmosphere and not fall to Earth. A cloud forms when humid air that contains water vapor is cooled. At cooler temperatures, air is unable to hold as much water as at warm temperatures, so some of the water is forced out of the air. It forms a droplet around a particle of dust in the atmosphere or, if cold enough, turns into ice crystals.

When the number of droplets becomes so dense that the cloud looks gray or black in color, it will probably produce precipitation. The cloud becomes darker in color because the water droplets are so dense that no light gets through.

Types of Clouds
Clouds exist in a variety of types. Each type of cloud forms under certain circumstances of temperature, pressure, and humidity. Visit our cloud gallery to explore the variety of clouds that appear in our sky.

The variety of cloud types not only makes them enjoyable to watch but, in fact, they can provide useful clues to the weather ahead. As you walk out your front door each day, take a quick survey of cloud types to prepare for the day’s weather. In general, small, white, thin cirrus clouds usually mean that snow or rain is unlikely, while large, dark cumulonimbus clouds mean that a storm is looming.