Definitions
Saturated Air
For a given atmospheric pressure, air holds more water vapour
at highertemperatures than lower temperatures.
The maximum amount of water vapour contained in a cubic metre
of saturated air decreases with a decrease in temperature.
At 40ºC it can contain 51 grammes, at 20ºC 17 grammes
and at 0ºC only 5 grammes.
Dew Point
is the temperature at which a sample of saturated air will
condense. Warm air can contain more water vapour than cold
air.
Relative Humidity
Expressed in percentage terms is the ratio of water vapour
present in a given sample against the saturated level. if
the Relative Humidity (RH) is said to be 100% then the air
sample is saturated.
Condensation
Occurs when moisture laden air releases its water vapour
on to the surrounding surfaces in the form of water droplets.
For condensation to occur the following conditions need to
be present:
· Temperature gradient (between air inside and outside
the container)
· Water vapour (moisture).
· Pathway for it to move.
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