Appendix A
Weather Data
Refer to this appendix to learn more about the weather variables that are measured, displayed, and logged by your Vantage Pro2 Station. Some weather variables require optional sensors. See “Optional Sensors” starting on page 2.
Wind
The anemometer measures wind speed and direction, and is part of the Integrated Sensor Suite (ISS). The console calculates a
Temperature
The ISS houses the outside temperature sensor in a vented and shielded enclosure that minimizes the solar radiation induced temperature error. The console houses the inside temperature sensor. Additional temperature sensors are available for wireless stations and can be used to measure up to eight locations.
Apparent Temperatures
Vantage Pro2 calculates three apparent temperature readings: Wind Chill, Heat Index, and the Temperature/Humidity/Sun/Wind (THSW) Index. Apparent temperatures use additional weather data to calculate what a human body perceives the temperature to be in those conditions.
Wind chill
Wind chill takes into account how the speed of the wind affects our per- ception of the air temperature. Our bodies warm the surrounding air mole- cules by transferring heat from the skin. If there’s no air movement, this insulating layer of warm air molecules stays next to the body and offers some protection from cooler air molecules. However, wind sweeps that comfy warm air surrounding the body away. The faster the wind blows, the faster heat is carried away and the colder you feel.
Heat Index
The Heat Index uses temperature and the relative humidity to determine how hot the air actually “feels.” When humidity is low, the apparent tem- perature will be lower than the air temperature, since perspiration evapo- rates rapidly to cool the body. However, when humidity is high (i.e., the air is more saturated with water vapor) the apparent temperature “feels” higher than the actual air temperature, because perspiration evaporates more slowly.
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