User Manual

Version 1.0 Page 37
Term
Definition
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.
To find the Heat Index temperature, look at the Heat Index chart below. As an
example, if the air temperature is 96°F and the relative humidity is 65%, the heat
index (how hot it feels) is 121°F.
IMPORTANT: Since heat index values were devised for shady, light wind
conditions, exposure to full sunshine can increase heat index values by up to 15°F.
Also, strong winds, particularly with very hot, dry air, can be extremely hazardous.
The Heat Index Chart shaded zone above 105°F shows a level that may cause
increasingly severe heat disorders with continued exposure or physical activity.
Heat Index is not calculated below 80°F.
HectoPascals
(hPa)
Pressure units in SI (international system) units of measurement. Same as millibars
(1 hPa = 1 mbar)