Normally the best time to capture fog and low clouds is in the early morning. This kind of weather is ideal for all kinds of outdoor scenes from landscapes to wildlife, and from architecture to people. This is Bled Castle in Slovenia, and when I photographed it I had to be conscious of the possibility that the mist and low clouds might cause underexposure. Therefore, I check the LCD monitor to determine if I needed to use exposure compensation. In this case, I used a +2/3 f/stop to correct the exposure.
You have to shoot fast in a situation like this because as the morning progresses, the air gets warmer and the fog burns off. The settings for this picture were 1/320, f/4, 400 ISO. I used a 70-200mm lens set to 200mm.