HUMIDITY
• The absolute humidity is the mass
of the water vapor in a given
volume of air or gas.
• It’s unit of measurement is grams
per cubic meter
RELATIVE HUMIDITY
• Relative humidity is the ratio of the amount of water
vapor in a volume of air compared to the amount
needed for saturation at the same temperature
• Saturation: a condition in which the amounts of precipitation
and condensation are equal
• Varies with temperature
• Expressed as a percentage
• Relative humidity=(actual amount of water/total amount the
air can hold) X 100
DEW POINT
• As the temperature rises, the amount of water vapor
the air holds also rises.
• If the temperature cools, the atmosphere cannot hold
as much water. When this happens, the water vapor
leaves the air in the form of liquid water, this is called
dew.
• Dew point- when the water vapor turns to liquids
• Varies each day and from place to place
• Depends on the temperature and amount of water in the air
HUMAN PERCEPTION
Dew
Human Perception
Over 80°F
Severely high. Even deadly for asthma related
75-80°F
Extremely uncomfortable
70-74°F
Very humid, quite uncomfortable
65-69°F
Somewhat uncomfortable for most people at upper edge
60-64°F
OK for most, but all perceive the humidity as being high
55-59°F
Comfortable
50-54°F
Very comfortable
Under 50°F
A bit dry for some