Proper usage of Solarmeter Ultraviolet Radiometer for Outdoor UV Index Measurement
The instrumentation used to measure UV index for the U.S. E.P.A./NWS program is directed toward the sky in a global normal (perpendicular to level ground) inclination. Therefore the Solarmeter® Model 6.5 is designed to operate in the same fashion. Solar irradiance measured this way includes direct (reduced by cosine law depending on solar zenith angle) plus diffuse (diffused by the atmosphere).
This vertical (global) reading represents an average intensity value your body will experience while being active on a tennis or volleyball court, or lying flat on a blanket on the grass. If however, you are reclined in a lounge chair facing the sun perpendicular to the sun angle, you will experience a higher UV intensity, as represented by pointing the Solarmeter ® directly at the sun. This value will typically exceed the actual UV index number.
Sensor: Silicon Carbide (SiC) Photodiode under UV glass window, hermetically sealed with Eeff (erythemally effective) filter and diffuser cap.