CV and mad panic behaviour

[Thryleon]

That is a matter for a person, not a demonstration of new strange physics during winter!

You can sit inside in the warm in a northerly aspect and get 30 ~ 60 minutes of midday sun, it still works through glass.

Its funny, how wrong we can be, and right we can be all at the same time.

https://www.solar-facts-and-advice.com/v...e-sun.html

2)    UVB radiation:  Your skin requires UVB radiation to produce vitamin D.  Since glass blocks UVB – this means you need to be outdoors in the sun.  As we discussed in our section on irradiance, UVB is produced by the sun; and in our section on insolation, the amount of the sun's radiation varies with latitude, altitude  (e.g. in Denver you need 20% less time in the sun because of the altitude), weather conditions, time of day, time of year, etc.

While it is generally true that you can produce solar energy – as long as there is visible sunlight, the research on producing vitamin D from the sun seems to suggest that there is a threshold level of UVB your skin requires in order to produce Vitamin D. 

In other words – depending on where you live - the number of days and hours where there is sufficient UVB radiation your sun can use to produce Vitamin D will vary.  So while it might take you 15 minutes in the peak (10:00 AM  to 2:00 PM) time in the summer to produce the vitamin D you need – it could take much longer than that in the spring and fall  (substantially more if the weather is still chilly and you are wearing more clothing), and may not be possible at all in the winter.