Clouds are the only landscape that never repeats itself. A cumulonimbus is a mountain that exists for an hour — taller than Everest, built of nothing but water and rising air — and then it is gone.

This is an ongoing study of the sky over Norway, photographed in 100-megapixel medium format. The resolution matters: at this scale, a cloud stops being a shape and becomes a structure. You can read the turbulence in its walls, the hard sunlit edges of a rising tower, the soft decay of an anvil spreading downwind.

I work the way one would photograph mountains — waiting for light, returning to the same skies through the seasons — except these mountains assemble themselves in front of the camera and dissolve before the day is over. Each photograph is titled by cloud type, place and year, in the tradition of landscape photography's precise regard for its subject.

The series continues. New work is added as the sky provides it.