Outdoor summer solstice readings

[solarmeter®]

Here's some readings from June 20 at Harrison Township, MI (~42N) for several meter models. Model 5.0 total UV, 6.2 UVB, 6.5 UV Index, and 6.4 D3 IU/min.

Note that rate of rise and fall of total UV (mostly UVA) is quite "flat" near solar noon, UVB is sharper, and weighted UVI and D3 the most sharp. The 5.0 readings have decimal point moved 3 places right to convert from mW/cm² to uW/cm² so they can relate better to the 6.2 values.

You can divide the 6.2 by 5.0 readings to see percent UVB changing from low to high as solar noon (about 1:45pm or ~14:00) approaches. Readings are pointing AT the sun.

Time...........5.0........6.2.......6.5.......6.4

08:00.........1800.......044......0.5.......03
09:00.........3100.......114......1.7.......12
10:00.........4500.......209......3.6.......26
11:00.........5600.......293......5.8.......41
12:00.........5700.......343......7.2.......51
13:00.........5700.......359......8.0.......57
14:00.........5800.......369......8.3.......59
15:00.........5700.......347......7.5.......54
16:00.........4800.......247......5.3.......38
17:00.........3500.......183......3.4.......24
18:00.........1900.......070......1.1.......08

Just yesterday the sky clarity was perfect deep blue and the UVI reached 9.3.... but I didn't have time to take all readings every hour. But the above clearly shows how the different bandwidths, unweighted and weighted, climb and reduce vs sun angles at different rates.
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