robert@xxxxxxxxxxxxxxxxxx wrote: > I also ran illumread with an early morning blue sky (winter, Ireland) which > I would have expected would have a fair amount of UV and this is what I got: > > http://www.irelandupclose.com/customer/LL/morning-blue-sky-permajet-oyster.jpg Hi, I'm not sure that morning sun has much UV either - typically the atmosphere intersecting sunlight is quite thick in the morning or evening, which is why UV exposure peaks during the day. See <http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/gif_files/diur_uv.gif> <http://en.wikipedia.org/wiki/Sunburn#mediaviewer/File:UV_Diurnal_Erythemal_Dose_Rate_Per_Latitude_graph.png> Graeme Gill.
