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I walk daily to my office and back during the week (except when the weather is atrocious). On clear sunny days, especially during the summer months, I’m exposed to a lot of sunlight, particularly on the left side of my face as I walk in a southerly direction in the mornings. Walking home, of course, still exposes the same side to more direct sunlight. Perhaps I should walk backward on the way home …
In what follows, the intensity of sunlight on the side of my head1 will be expressed in terms of the solar zenith angle θ for consistency with the clear-day model mentioned in question 2. Assume that the sky is cloudless.
Question 1: If I0 is the solar irradiance (power per unit area, W/m2) reaching my head, express the intensity on the side of...
