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I looked out my window a minute ago and immediately noticed a very bright spot where a cloud and a jet/plane trail met. The spot was so bright that I thought the sun was behind it because it left that typical "burn-in shape" in my vision even when I closed my eyes from the brightness.

However, I mentioned something about it (since it looked neat) and the other person mentioned that that spot was not the sun, the sun was over out of my field of view. This spot was an intense reflection of the sun.

I rushed to grab my camera and photo this since I've never seen anything like it before, but the reflection didn't last long enough (though the clouds just moved a little).

I'm not sure what type of chemicals are used in jet fuel, but was this reflection from the water in the clouds - or something in the fuel?

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1 Answer 1

Cloud albedo, the ability to reflect solar radiation, can reach as high as 90% due to reflection from water droplets according to Wikipedia. Additionally, jet trails (contrails) are made up of water or ice droplets and could also exhibit significant albedo.

It seems very possible that for optimum Sun-cloud-viewer geometry, with the Sun behind the viewer, a cloud could appear very bright for a short period of time from reflected sunlight until the geometry changed from cloud movement.

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Thanks for the explanation. In this case the sun was more like 45° to the left. Just enough to place it out of my windows' field of view. I know water can reflect a huge amount of light - but I wasn't sure about vapor. –  Xeoncross Nov 21 '12 at 16:51

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