Tuesday, 1 April 2008

What colour are clouds?

(No pics for a while - I'm on a 2 week business trip)

Not a philisophical question, more a matter of the meeting of physics and neuroscience. As we flew over the clouds this afternoon, I seemed to be seeing all sorts of colour illusions. The sun behind us was reflecting off the south-facing aspects of the clouds. In the distance a veil of cloud appeared to have pink hues. The sky was pale blue in between.

That got me thinking - how does one get an accurate sense of clouds in a print that includes a lot of sky? I'm sure the mind plays tricks - telling you the colours you expect to see. But on the other hand, when viewing the sky we see refracted light, reflected light, diffused light, re-reflected light etc. In terms of colour, these should all have different temperatures. Then when we come to print an image of this, it is all reflected light: uni-directional. In to that mix, does the brain interpret phase changes (from the refelctions) differently than the direct light (sort of like a built-in polarizer)?

I wish I knew some of the answers here - I'm never entirely satisfied by the way my skies look in colour print. Has someone written a definitive guide to the colour fidelity of skies?

On a lightly related note: clouds a re wonderful structures. That hanging balance of saturated and condensing air. The subtle shifts in conditions that cause minute droplets to form. It was particularly spectacular today with the top surface of the clouds fluffy like a giant carpet of cotton wool.


  1. In a moody picture, a painter will often use the same pallet of colours for clouds, land and water. This has the effect of tying in the different elements. Clouds are colourless and only reflect colour from below, or from some tangential location (e.g. sunsets).

  2. I used to fly sailplanes, and I never got tired of watching the clouds when I was flying. When you get up close, they are absolutely stunning. I have flown quite much in the mountains where the conditions often allows the sailplanes to get up between the clouds. It can be dangerous, but marvelous. My domain (and blog) is named after one of these cloud formations.

    Unfortunately, my active gliding years was when my photography interest was at its lowest. Not many photos to show for, and certainly not digital.

    cheers ..


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