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All About

Clouds are made of drops of water or ice. When the wind picks up water from the ocean or from the land on Earth, it can carry the water up into the sky. If there’s a lot of water drops together, most of the sunlight that hits the reflects off the water or ice. Then the light reaches your eyes, where it looks white. In a thick cloud, the water drops scatter the light in all directions instead of reflecting it. Then not all of the light reaches your eyes, so the cloud can look gray or black.

Clouds can happen at any height above the ground. Sometimes clouds are actually touching the ground. We call that . If you go up to the top of a mountain or in an airplane, you will be above most of the clouds. After it , the clouds disappear, because the water they were made of has all come back down to Earth again. On Earth, there are four main types of clouds: cumulus, stratus, cirrus, and nimbus (the most common of these being cumulonimbus clouds).

Cumulus clouds are clouds that are piled up on top of each other. “Cumulus” means a pile in Latin, as in our word “accumulate” meaning to pile up. They are puffy clouds. Sometimes cumulus clouds are white and there are only a few of them in the sky; other times they can be heavy and gray. They’re usually low-level clouds, only about 1000 meters (3300 feet) above the ground.

Usually you get cumulus clouds when warm air rises from the ground carrying water vapor with it by evaporation. When the warm wet air rises up and meets some cold air, the water vapor gets colder and condenses into drops of water, making a cloud.

When cumulus clouds are white and puffy, that usually means it’s not going to right away. But if they grow into big gray clouds, you can expect rain. White clouds are thin and let a lot of sunlight through them – that’s why they look white. Gray clouds are thicker, with more water. Less sunlight gets through them.

If you see stratus clouds, that’s the time to get inside and stay there. Stratus clouds mean rain if it is warm and if it is cold. They look like a huge gray blanket that hangs low in the sky. Sometimes stratus clouds are on the ground or very near the ground, and then we call them fog.

Source: https://quatr.us/history/clouds-made-weather-science.htm Usually stratus clouds and fog form when it has been cold out and then warmer, wet air blows in. As the warm air flows over the cold ground or over the cold air near the ground, the water vapor in the warm air condenses into drops of water that make a cloud. How thick the cloud is depends on how wet the air is and how big the difference in temperature between the cold air and the warm air is.

Most of the time, you see cirrus clouds very high up in the sky, looking thin and wispy, like someone pulled a bigger cloud apart into little bits of cloud. Cirrus (SIR-russ) clouds look thin because they are made of ice crystals, not water drops. They form where it is high enough to be cold and freeze the water drops into ice. Sometimes you might think you see cirrus clouds when it’s really only the trail of an airplane, half blown away and spreading across the sky. But either way, if the sky is blue with only these thin cirrus clouds high up in it, you can be pretty sure it’s going to be a nice day.

Nimbus clouds often mean that a thunderstorm is brewing: there may soon be thunder and lightning. Get out of the swimming pool! Nimbus is a fancy word, but it really just means a cloud that already has rain or snow falling out of it. Can you see the rain falling from the in the picture to the right?

Clouds don’t have to be just one kind of cloud – they can be more than one type at the same time. So you often see the names of clouds combined: a cumulonimbus cloud is a , a puffy thick cloud, with rain falling out of it, and a stratonimbus cloud is a stratus cloud, a gray blanket cloud, with rain falling out of it.

On other planets, there can be clouds made of things other than water. Venus is covered by thick clouds, but the clouds there are made of drops of sulphuric acid, chlorine, and fluorine, and would be poisonous to you.

Source: https://quatr.us/history/clouds-made-weather-science.htm