I must correct myself about sun exposure and vitamin D production. Several resources have shown that to maximize your vit D production and minimize your risk for melanoma, the best sun time is to go out at noon! But don't stay out long enough to burn, bc then you do increase your risk for another type of skin cancer.
I'm just going to quote here:
" First of all, you need a shorter exposure time because the UVB is more intense. Now, the second reason is that when the sun goes down towards the horizon, the UVB is filtered out much more than the UVA. And it turns out that the long wave of ultraviolet called UVA, which runs from about 320 to 400 nanometers, is highly correlated with melanoma -- where the UVB is the one that produces the vitamin D, and that’s from 290 to 315 nanometers,”
SO UVB penetrates the skin to make vit D, and those rays are the strongest during the middle of the day.
Here is the whole article if you are interested, When Should You Go Out in the Sun?