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ATMOS 41
good accuracy regardless of temperature or sensor age. Silicon-cell sensors have excellent
response time to changing radiation conditions and acceptable sensitivity across the solar
spectrum, which make them perfect for use on the ATMOS 41.
Leveling the ATMOS 41 is particularly important for accurate solar radiation measurements.
Out of level, the pyranometer will overestimate some portions of the day while under-
estimating others. Ensure accurate solar radiation measurements by carefully leveling the
ATMOS 41 at installation. Bird droppings and other soiling of the domed sensor surface will
cause serious errors in pyranometer measurements. Regularly check the sensor to make
sure it is clean and check data often to identify possible problems. Isopropyl (rubbing)
alcohol and a Q-tip work well for cleaning the sensor area. Do NOT use an abrasive cloth on
the sensor surface, as it will scratch. Microfiber bags work well too.
The pyranometer is factory calibrated and the sensor-specific calibration value can be found
on the interior of the rain funnel. This factor has already been added into the ATMOS 41 so
there is no need to do anything with it. But, in the event that this value is needed, it can be
found by taking the funnel off the base and checking underneath.
3.3 ANEMOMETER
The space underneath the rain gauge is where the ATMOS 41 measures wind speed.
Ultrasonic signals emitted from transducers at right angles to each other bounce off
the porous sintered glass plate (
) and back up to the opposite sensor. The
speed of sound is affected by the wind, and the wind speed is calculated by measuring
differences in the time it takes for sound to travel back and forth between sensors
(see
).
Figure 4 Anemometer
