How do clouds stay afloat

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Accessibility Links Skip to content. Why do clouds form? Do clouds fall to the ground? Why do clouds sometimes disappear? Clouds are created from water vapor that condenses into water droplets, and warm air and water vapor will rise above the cold air around it 1. Your breath on a chilly winter day or the steam from a tea kettle are examples of water vapor that rises.

Are clouds warmer than the surrounding air, and if so, what makes clouds warm? The warm, moist air is less dense than the cold air above it, so that warm air rises 2. The warm air cools as it comes into contact with the cooler air above. Cold air cannot hold as much moisture as warm air: the vapor has to condense into a liquid.

This is the beginning of a cloud. The sun heats the earth, and causes water on the ground to evaporate 3. So it could carry up to about tonnes of water.

There are three main reasons. First, the heat of the Sun warms the ground, which then creates rising currents of air. Second, an advancing storm or weather front running close to the ground can push the air that it runs into upwards. Third, air carrying water vapour can run into a mountain and rise, adding buoyancy to the cloud above. Air when it is moving very fast can easily hold up a tonne jet plane.

So a huge volume of slowly moving air can definitely hold up a tonne cloud. A very dark cumulus cloud can look like a hill. There are three pieces to this puzzle, and the first one is gravity.

Like everything on this planet, the tiny droplets that make up a cloud are drawn towards the Earth by gravity. And any wind blowing upwards can carry the droplets back up. Let me introduce the periodic table: a map of all the elements that we humans know about. Elements are the building blocks of all things — just like the smallest pieces of Lego, which you use to build bigger and more complex objects.

The periodic table is organised so that the lightest element of each row is always on the left. As you move along each row from left to right, the elements get heavier and heavier. Click here for a larger, interactive version. Dry air is mostly made up of two gases, nitrogen and oxygen, plus a little bit of argon and tiny amounts of other gases. For now, we can just focus on nitrogen and oxygen. As you can see on the periodic table, the weight of a single nitrogen atom is 14, while oxygen weighs almost But neither nitrogen nor oxygen atoms like to be alone, so they almost always go in pairs — two atoms in a molecule, like two peas in a pod.