What is the difference between dewpoint and relative humidity?
Dewpoint (Td) and relative humidity (%RH) are two different ways of expressing the amount of water vapor in the air. Dewpoint is defined as the temperature to which the air must be cooled, at constant pressure, for water vapor to begin to condense to water. In other words, when the dewpoint temperature has been reached, the air is fully saturated with water vapor. Relative humidity is defined as: %RH = (pw / pws) x 100 Where: pw = partial pressure of the water vapor pws = saturation vapor pressure of water vapor at a given temperature Relative humidity is a percentage describing the ratio of the amount of water vapor in the air to the maximum amount of water vapor the air can hold at a given temperature. For example, a relative humidity of 70% indicates that the air contains 70% of the maximum amount of water vapor it is capable of holding at that particular temperature. When RH = 100%, the air is fully saturated and the air temperature = dewpoint temperature. Relative humidity will va
