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What Is Humidity?

Humidity is the amount of water vapor in the air. The cause of humidity is water evaporating and turning into tiny droplets that become suspended in the air. The droplets are so tiny that they have the characteristics of a gas instead of a liquid. Relative Humidity (RH) is a measure of how saturated the air is at its current temperature. Since warm air can “hold” more water vapor than cool air, the RH of warmer air will be lower than cool air, even with the same amount of water vapor.

When the relative humidity is high, the air feels damp and sticky. You might have noticed that the air feels this way after a summer rain when the sun comes out and begins evaporating the water or right before a summer storm. This is because the air is becoming more saturated with water vapor.

As RH reaches 100%, it begins to condense and fall as rain.

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