Interested in this since I sometimes look down on the clouds in the plane, and wonder if some of the reflected UV-A radiation might damage my eyes.

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    $\begingroup$ The type of cloud provided in the question is misleading. For exemple, when you say cumulus, you speak about cumulonimbus, stratucumulus, altocumulus or cirrocumulus? Moreover, there are different type of stratus cloud. Each of them will have a different relationship with respect to reflection of UV radiation. This kind of precision is needed to answer your question. $\endgroup$
    – Balinus
    Aug 8, 2014 at 16:52
  • $\begingroup$ @Balinus -Late to comment on this but totally agree with your comment $\endgroup$
    – user1066
    May 18, 2018 at 8:50
  • $\begingroup$ @Balinus -i agree with you. There are a lot of different type of cumulus and stratus clouds with all other characteristics. It is an interesting question though $\endgroup$
    – 3TW3
    Sep 29, 2018 at 19:55
  • $\begingroup$ the type of uv light is important for its properties,is the question about UV-A only.shorter wavelenght UV never reaches as deep into the atmosphere as to where the clouds are,and the longest wavelenght UV is only scattered by clouds and not realy reflected. $\endgroup$ Oct 3, 2018 at 6:33

1 Answer 1


According to the below albedo rating diagram (percentage is reflection of incident radiation) cumulus cloud is the greater total spectrum reflector so it will reflect more UV that equivalent stratus formations.

enter image description here

Do note that water vapour does however absorb the vast majority of UV (≈100nm) that it intercepts as we can see in this diagram:enter image description here

So overall cloud UV reflectance will be quite low.

  • 1
    $\begingroup$ Can you clarify what's the y axis in the first figure? $\endgroup$
    – Gimelist
    Oct 2, 2018 at 9:12
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    $\begingroup$ @Gimelist Sure it's total reflection as a percentage of incoming radiation. $\endgroup$
    – Ash
    Oct 2, 2018 at 12:26
  • $\begingroup$ @Ash can you share the source of the figures please ? $\endgroup$
    – Ayoubayjx
    May 30, 2021 at 15:18
  • 1
    $\begingroup$ @Ayoubayjx The first is from Wikipedia's albedo article the second one I'm not sure where I sourced it but it appears to have been compiled by Martin Chapman. $\endgroup$
    – Ash
    Aug 31, 2021 at 3:51

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