For folks living in the Desert Southwest, it seems almost like common sense to wear light-colored clothing out in the sun. But then we see photos like these, of Bedouin or Taureg people wearing black.
Are they crazy? Or do these desert-dwellers know something that we don't know?
Or, this letter at nature.com. Folks in Albuquerque, a kinda windy place, but with quite warm, dry summer days, might want to take note of the reference to wind speeds; a little breeze, and loose clothing (dark or light), appear to be key factors.