After having pretty much no sun for weeks (5.2 h since the 6th of Dec), today was finally sunny and immediately gave interesting results. My anemometer returned no data for some time as the cups froze solid, but there was some wind around sunrise (around 5 km/h from what I can tell from official stations and interpolation). There was a period from 11:00 to 12:30 where the SC went as much as 0.8C cooler than the Davis and this was with low/moderate wind and low sun, so completely the opposite of what you'd expect, as you'd expect the passive shield to be warmer than the active one in such a scenario. I think the main reason for this is that there was ice on the plates of the SC and the ice was in the process of melting, something that requires energy, and I suspect the melting process extracted that energy from the incoming air into the shield. Before and after the melting process, the shields ran basically the same, despite the continuous low/moderate wind (5-10 km/h at 5 m height) and low angle winter sunshine. Imo, this is some evidence that the low sun angle effect does not occur on the SC with wind speeds of 5-10 km/h. As for the strange cool period on the SC, this shows the advantage the Davis design has with drawing in air from below, as it can't be influenced from water/ice/heat/whatever from the plates.
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