Science explained

Humidity, relative humidity and dew point

Humidity describes water vapour in air, but relative humidity and dew point answer different questions.

WeatherHumidity

Editorial review: August 12, 2026 · Julian E. Marston

Relative humidity depends on temperature

It compares actual water vapour with the amount associated with saturation at that temperature.

Dew point tracks moisture more directly

It is the temperature to which air must cool to reach saturation under specified conditions.

Cooling can raise relative humidity

The amount of water vapour can stay the same while relative humidity increases.

Condensation appears at surfaces or in clouds

When air reaches saturation, liquid droplets or ice can form under suitable conditions.

This page explains scientific concepts for general learning. It does not replace laboratory safety procedures, professional engineering guidance, or individualized medical advice.