when inclined high enough for vit d production

For those of us in northern climes vitamin d production stops for several months, as the inclination of the sun isn't high enough for the required uvb spectrum to penetrate.

It would be brilliant to see some indication of the penetration (all be it that it is then blocked by cloud, ozone etc).

At worst a degrees indicator would let us see when it gets that vital 50 degree mark, and for how long each day.

Apart from that I absolutely LOVE your program - really interesting :)