Davis Instruments GroWeather, Руководство пользователя

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Weather Conditions Measured/Calculated
GroWeather Manual Page 9
Wind
The GroWeather measures wind speed, wind direction, and wind run. Wind
run is a measurement of the “amount” of wind which passes a given point (the
anemometer) during the measurement period. It is expressed as either “miles
of wind” or “kilometers of wind” and is determined by calculating the integral
(summation) of wind speed multiplied by the time of the measurement period.
For example, if the wind blew at an absolutely steady 10 MPH for 12 hours,
you would have 120 miles of wind run (speed x time = 10 MPH x 12 Hours =
120 miles). Wind speed changes over time, so wind run is calculated by adding
together (summing) the distance (speed x time) for every single speed and time
reading during the measurement period. In practice, however, the GroWeather
simply keeps count of the number of revolutions made by the wind cups dur-
ing the period and multiplies that number by a scale factor which gives a wind
run reading in either miles or kilometers.
• Current Wind Speed (Alarm: High)
• “Daily” Wind Run (AutoClear)
• Average Wind Run per day during period
• Wind Direction
• High Wind Speed with time and date of occurrence and direction of high (Auto-
Clear)
Solar Radiation
What we call “current solar radiation” is technically known as Global Solar
Radiation, a measure of the intensity of the sun’s radiation reaching the earth’s
surface. This irradiance includes both the direct component from the sun and
the diffuse component from the rest of the sky. The solar radiation reading
gives a measure of the amount of solar radiation hitting the solar radiation sen-
sor at any given time, expressed in Watts per Square Meter (W/m
2
). The power
of this radiation, when integrated (summed) over a period of time, gives a
measure of the amount of incident solar energy received during that time
period. This solar energy reading is expressed in Langleys.
Note: The GroWeather measures energy received in the spectral band between 400 and 1100 nm.
• Current Solar Radiation Intensity
• “Daily” Incident Solar Energy Sum (AutoClear)
• Average Incident Solar Energy per day during period
1 Langley = 41.84 kiloJoules per square meter
= 11.622 Watt-hours per square meter
= 3.687 BTUs per square foot