Have you ever played the cloud game? You lie on the grass and look up at the clouds. You try to see different shapes in the clouds. One cloud might look like the head of a horse. Another might look like a car. You watch as the clouds move across the sky. You watch the clouds change shape as they move.
WHAT ARE CLOUDS MADE OF?
Clouds are made of small drops of water or tiny pieces of ice. The water and ice in clouds come from Earth’s surface, especially from lakes, rivers, and oceans. Water on the surface evaporates. It changes into a gas called water vapor. Water vapor goes up into the air.
The higher up you go, the colder the air gets. When water vapor gets cold, it changes back into drops of water. If it gets cold enough, the water changes to ice.
The water droplets and bits of ice are so small that they float on the wind. You see the water and ice in the sky as clouds. Strong winds and gentle breezes make different kinds of clouds.
WHAT ARE THE DIFFERENT KINDS OF CLOUDS?
Clouds that form in calm air look like flat sheets or layers of sheets. Clouds that form in strong winds tower up high in the sky.
Meteorologists (scientists who study weather) group clouds into four families. Three families are called high clouds, middle clouds, and low clouds. These three families form at three different levels in the sky. The fourth family is made up of towering clouds that go up through the three levels. Meteorologists have grouped about 100 types of clouds into these four families.
HIGH CLOUDS
High clouds are made of bits of ice. High clouds can be 5 miles (8 kilometers) or more above Earth’s surface. There are three main types of high clouds. Cirrus clouds are thin and feathery looking. Cirrostratus clouds look like a misty, flat veil or sheet. Cirrocumulus clouds look like groups of small, white cotton balls. Rain and snow do not fall from these clouds.
MIDDLE CLOUDS
Middle clouds are made of water droplets. They form about 2 to 4 miles (about 3 to 6 kilometers) up in the sky. There are two main types of middle clouds. Altostratus clouds are like a gray or bluish sheet of frosted glass across the sky. You can see through them, but they make the Sun and the Moon look blurry. Altocumulus clouds look like big wads of white fuzz.
LOW CLOUDS
Low clouds are made of water droplets. Most low clouds are less than a mile (1.6 kilometers) high. There are three main kinds of low clouds. Stratocumulus clouds are soft, gray rolls of clouds. They often cover the whole sky. Stratocumulus clouds are not very thick, so blue sky sometimes peeks through the clouds. Nimbostratus clouds are thick, dark, and shapeless. They are gloomy-looking clouds. Rain or snow usually falls from these clouds. Stratus clouds are really fog up high. They look like gray blankets. These clouds often break up, letting you see blue sky beyond.
TOWERING CLOUDS
Towering clouds stretch through the low, middle, and high cloud layers. There are two main kinds of clouds in this group. Cumulus clouds have flat bottoms and rounded tops that look a little like cauliflower. Cumulonimbus clouds are dark, heavy-looking clouds. They rise up like mountains high into the sky. Sometimes the tops of these clouds spread out at the top. The top is made of ice. Cumulonimbus clouds are also called thunderheads. These clouds bring thunderstorms and sudden, heavy rains.
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