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| types of Clouds |
Clouds are made up of very light water droplets or ice crystals. These particles can float in the air. When warm air rises, swells and cools, it forms clouds. Many water droplets formed together scatter reflect sunlight and you see a white could, but with a dark or gray cloud, the sunlight is scattered in all directions instead of reflected. The different types of clouds are cumulus, cirrus, stratus and nimbus.
**Cirrus Clouds
Cirrus clouds are the thin, wispy clouds seen high in the sky. They look as if someone took a cloud, stretched it, pulling pieces off, like a cotton ball when it is pulled apart. They are thin because they are made of ice crystals instead of water droplets. A blue sky and a few cirrus clouds high in the sky, usually means it is going to be a nice day.
**Cumulus Clouds
Cumulus clouds are the puffy clouds that are usually scattered throughout the sky. In Latin, the word cumulus means pile. Just like when we say “accumulate,” it means things pile up. This type of cloud is formed when warm air rises carrying water vapor with it by evaporation. Cumulus clouds can be white or gray. White fluffy clouds means no rain, but when they form into dark or gray clouds, it is going to rain. Cumulus clouds have sharp outlines and a flat base at a height of 1000m.
**Cirrocumulus clouds are small rounded puffs that usually appear in long rows high in the sky. Cirrocumulus are usually white, but sometimes appear gray. They are the same size or smaller than the width of your littlest finger when you hold up your hand at arm's length. When these clouds cover a lot of the sky, they can look like the scales of a fish, which is it is called a "mackerel sky.” Cirrocumulus are common in winter and indicate fair, but cold, weather.
**Cirrostratus clouds are high, thin sheet-like thin clouds that usually cover the entire sky. The clouds are so thin that the Sun or moon can sometimes shine through and appear to have a halo as light hits the ice crystals and bends. The halo is the width of your hand held at arm's length. Cirrostratus clouds usually come 12 to 24 hours before a rain or snowstorm.
**Stratus Clouds
Stratus clouds look like a huge thick blanket covering the sky. These clouds are a sure sign of rain if it is warm and snow if it is cold. If stratus clouds are near the ground, they form fog. These clouds form when the weather has been cold and warmer moist air blows in. The amount of moisture in the air and the difference between warm and cold air determine how thick the cloud or fog is.
**Nimbus Clouds
The word nimbus means a cloud that already has rain or snow falling from it. These clouds are dark and seen during a thunderstorm along with thunder and lightning. They can be a combination of two clouds, like a cumulonimbus, which means a puffy black cloud with rain falling out or it, or a stratonimbus, which is a dark blanket with rain falling out of it.
**Cumulonimbus clouds also have vertical growth and can grow up to 10 km high. At this height, high winds will flatten the top of the cloud out into an anvil-like shape. Cumulonimbus clouds are thunderstorm clouds and are associated with heavy rain, snow, hail, lightning, and sometimes tornadoes.
**Altocumulus clouds are mid-level, grayish-white with one part darker than the other. Altocumulus clouds usually form in groups and are about one kilometer thick. Altocumulus clouds are about as wide as your thumb when you hold up your hand at arm's length. If you see altocumulus clouds on a warm, humid morning, there might be a thunderstorm by late afternoon.
**Altostratus clouds are mid-level, gray or blue-gray clouds that usually covers the whole sky. The Sun or moon may shine through an altostratus cloud, but will appear watery or fuzzy. If you see altostratus clouds, a storm with continuous rain or snow might be on its way. Occasionally, rain falls from an altostratus cloud. If the rain hits the ground, then the cloud has become a nimbostratus.
**Mammatus clouds are pouches of clouds that hang underneath the base of a cloud. They are most often associated with cumulonimbus clouds that produce very strong storms. These clouds usually form during warm months, and are formed by descending air in the cloud. Mammatus clouds are sometimes described as looking like a field of tennis balls or melons, or like female human breasts. In fact, the name "mammatus" comes from the Latin word mamma, or breast.
**Lenticular, or lee wave, clouds form downwind of an obstacle in the path of a strong air current. In the Boulder, Colorado area, the obstacle is the Front Range of the Rocky Mountains, seen at the bottom of the picture. Wind blows most types of clouds across the sky, but lenticular clouds seem to stay in one place. Air moves up and over a mountain, with the lenticular cloud forming just past the mountaintop. The cloud evaporates on the downwind side, so it appears stationary even though air is moving through the cloud. Lenticular clouds are lens-shaped and often look like flying saucers.
**Kelvin-Helmholtz clouds look like breaking waves in the ocean. After wind blows up and over a barrier, like a mountain, the air continues flowing through the atmosphere in a wavelike pattern. Complex evaporation and condensation patterns create the capped tops and cloudless troughs of the waves. These clouds form when there is a difference in the wind speed or direction between two wind currents in the atmosphere.
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