I was of the mindset that elevation was more of a factor in UV index than latitude, but I just learned differently. Thank you. I found a nice discussion of the

I was of the mindset that elevation was more of a factor in UV index than latitude, but I just learned differently. Thank you. I found a nice discussion of the calculation: https://www.epa.gov/sunsafety/calculating-uv-index-0 https://www.epa.gov/sunsafety/calculating-uv-index-0 It hand waves a bit on how latitude is factored in but states clearly that every km of elevation increases exposure by about 6%. Mexico City: 2,240 m London: 25 m So 12% more UV for Mexico City based on elevation. The elevation is important but not the primary factor. Anecdotally, I have been in Mexico City. I did most of my walking in the mornings and still would sunburn on an sixty minute walk. I did not use any protection.