A Moment of Science

How Clouds Float

Learn how clouds float on this Moment of Science.

One thing we at A Moment of Science love is having the opportunity to explain the science behind things you see every day in the world around you. For example, if you happen to be driving or standing near a window, take a look up at the sky. See any clouds? If so, ask yourself this: how do clouds stay up in the air?

It’s a good question, and here’s why. Clouds are made of water droplets and ice crystals. Together, these droplets and crystals weigh many tons. So if the typical cloud actually weighs as much as an elephant, why doesn’t it plummet to the ground?

Unlike an elephant, a cloud’s weight is spread out over a very large area. Plus, the cloud’s droplets and crystals are very small–about one micron, or one-hundred-thousandth of an inch across. A cloud’s individual particles are so small, in fact, that warm air rising from the earth’s surface is able to keep them floating in the air. It’s similar to how dust motes swirl in a shaft of sunlight. Although the bits of dust are affected by gravity, even the gentlest air currents are enough to keep them dancing around in the air.

But clouds don’t stay up in the air forever, of course. When the warm air keeping clouds afloat cools, its water vapor condenses and adds to the cloud’s droplets. At a certain point the droplets become heavy enough to overwhelm the force of the rising air, and all that water falls to the ground.

  • Harry Potter

    WOW that’s amazing because God almighty mentioned that in the Quran 1400 years ago: “It is Allah Who sends the Winds, and they raise the Clouds: then does He spread them in the sky as He wills, and break them into fragments, until thou seest rain-drops issue from the midst thereof: then when He has made them reach such of his servants as He wills, behold they do rejoice!” Surah al-Room verse 48.

  • Gerda Taro

    Cool story, brah. I’m sure that the man upstairs totally did that, along with approving of making his followers blindly follow based on a conviction of faith in the absence of any damningly strong evidence.

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