Purdue/12 August 2008

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Performed UV flux test using instrument from Apogee Instruments (Model QMSW-SS). Measured photon flux on sunlight mode. The UV index for today is 3. At 3:20 pm, 700 umol/(m^2*s) was measured for pure cloud cover. 2000 umol/(m^2*s) was measured for pure sunlight. The Apogee website states that ~8.5% of sunlight flux is UV radiation. Accounting for the fact that only about 1% of UV radiation hitting the earth's surface is UVB (dimer-causing), these numbers convert to about 0.725 J/m^2*s in full sunlight and 0.264 J/m^2*s in cloud cover, which is fairly reasonable compared to literature.

Edited by Janie Stine