University of Illinois Extension

Moisture in the Air – Humidity

 Humidity in a field

Humidity in a field
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Water is present as a liquid and as a gas in the atmosphere. When water is a gas, it is called water vapor. You can’t see water vapor in the air, because water molecules are very small. When water is a liquid, you can see it in the form of clouds. It can also fall from the sky as precipitation.

The amount of water vapor in the air is called humidity. The amount of water vapor the air can hold depends on the temperature of the air. Warm air can hold more water vapor, while cold air cannot hold as much.

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