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Meteorology
3.5.3.1 Absolute humidity
The chart below shows the relationship between temperature and water
content in saturated air. It indicates how many grams of water vapor 1 m³ of
air can hold at different temperatures.
For example, the chart
shows that 1 m³ of air
at 10°C contains a
water vapor amount
equivalent to the size
of 10 sugar cubes and is
fully saturated with
water vapor.
Additional water vapor
will cause condensation.
By knowing the humidity level and temperature, you can calculate the absolute
humidity using the curve for corresponding values of temperature and water
content in saturated air.
3.5.3.2 Relative humidity
Humidity can also be expressed as a percentage of the amount of water vapor
present compared to the maximum amount the air can hold.
For example:
If 1 m³ of air at 10°C contains 8g of water vapor, and the saturation point is at
10g, you can say that the humidity content is 80%.
In saturated air, the relative humidity is always 100%.
The absolute water content of a given air volume depends on the temperature.
Relative humidity is measured using a hygrometer.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 269
