Humidity,
dewpoint and temperature measurement instruments
Relative humidity (RH)
is defined as the ratio of the water vapor pressure or water vapor
content to the saturation vapor pressure or the maximum vapor content
at the temperature of the air or gas. The saturation vapor pressure
in the air varies with air temperature, the higher the temperature,
the more water vapor it can hold. When saturated the relative humidity
in the air is 100 %RH.