Glossary Of Terms - Ambient Weather WS-2902B User Manual

3. Select Create Device and enter your weather station information. After registering your
station, make a note of the following:
•
Weathercloud ID
•
Key
Enter the Weathercloud ID (ID), Key (password) into the Ambient Tool. Leave the Station Number
(StationNum) blank.

9. Glossary of Terms

Term
Absolute Absolute pressure is the measured atmospheric pressure and is a function of altitude,
Barometric and to a lesser extent, changes in weather conditions.
Pressure
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 is a comparison between measurements – one of known magnitude or
Calibration
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.
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