Review on Supco EM20 Anemometer Velocity Temperature by Aaron Schultz

This unit works as advertised but is NOT intended for outdoor use so I bought it. It gets four stars because it does what it's supposed to do, but if you want to use it outside, buy something else. It turns out that the sensor for the anemometer is based on measuring how many times the leaves of a leaf pass a pair of UV SENSITIVE sensors. Under direct sunlight and bright indirect sunlight, these sensors measure no change in illumination as leaves pass. This reduces the speed to ZERO. Go into the shade and the device will start working again. The product is good and works exactly as advertised and is probably a great HVAC tool, however it does not work in direct sunlight.