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Figure 33
7.
Glossary of Terms
Term
Definition
Absolute
Barometric
Pressure
Absolute pressure is the measured atmospheric pressure and is a function of altitude,
and to a lesser extent, changes in weather conditions.
Absolute pressure is not corrected to sea-level conditions.
Refer to Relative
Barometric Pressure.
Accuracy
Accuracy is defined as the ability of a measurement to match the actual value of the
quantity being measured.
Barometer
A barometer is an instrument used to measure atmospheric pressure.
Calibration
Calibration is a comparison between measurements – one of known magnitude or
correctness of one device (standard) and another measurement made in as similar a
way as possible with a second device (instrument).
Dew Point
The dew point is the temperature at which a given parcel of humid air must be
cooled, at constant barometric pressure, for water vapor to condense into water. The
condensed water is called dew. The dew point is a saturation temperature.
The dew point is associated with relative humidity. A high relative humidity
indicates that the dew point is closer to the current air temperature. Relative
humidity of 100% indicates the dew point is equal to the current temperature and the
air is maximally saturated with water. When the dew point remains constant and
temperature increases, relative humidity will decrease.
Heat Index
The Heat Index, sometimes referred to as the apparent temperature, is a measure of
how hot it really feels when relative humidity is factored with the actual air
temperature.
