• You would need to indicate what latitude you are considering, and the day... as the earth rotates the angle shifts significantly enough each day that the answer will change day by day for each latitude.
  • It does not matter whether you are on daylight savings time or not. The most ultraviolet light will reach the surface when the sun is at its zenith. What time that will be depends on where you are within your time zone. So, without know where you are, it would be impossible for one of us to tell you when this would be for your location. However, you can figure it out for yourself. Most (if not all) local newspapers include in their weather reports the times for sunrise and sunset. Find this for your local area and calculate the time that is halfway between the two times. This is the time at which the Sun will be at its zenith for your area. For example, here in Laredo, Texas, sunrise today was at 6:42 and sunset will be at 20:33. So, there will be 13 hour and 51 minutes of daylight. Half of that is 6 hours and 55.5 minutes. Add this to the time of sunrise and I get the sun reaching its zenith here at about 13:38 or 1:38 pm today. So this is the time at which the ultra violet radiation would be most intense here today. Now go and figure this our for your area.
    • RondoHunter
      My thinking as well. Therefore a great answer!
  • 12-05-2016 You really need to give some thought to your question. Daylight saving time has nothing to do with reality except that heaters have to be turned on an hour sooner. (Classrooms need heat more than they need cooling.) And ultraviolet light to the ground depends more on dust in the air than anything else.

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