Jenny and I have just returned from Austria where we took a group to paint Alpine scenery. It was a great trip, with many memorable scenes, despite rather a lot of cloud and mist. So we had rather a lot of practice in rendering misty mountains in watercolour!
Mist on mountains can, for the artist, sometimes be both magical and a misery. I love the way it can blot out unwanted features, but as we all know, it often blots out the very features we want to see!
There are a number of ways of creating mist in watercolour. In this scene above the Inn Valley I ran colour into wet areas to create soft edges to the clouds. I had to work quickly as I was painting on a cartridge book. With such a lot of cloud edges, inevitably some dry hard-edged before they can be corrected, but this is not usually a problem as they can later be softened with a damp brush when the paper is completely dry, though the odd hard edge here and there might well enhance the clouds. Alternatively a soft sponge is an excellent tool for softening off, but take care if you use cartridge paper as it won't stand too much surface friction. Enjoy your clouds!