In early Fall you can experience the phenomenon of a steaming river. This happens when the morning is quite chilly and there is high humidity. The water in the river is still relatively warm and thus it starts steaming in the cold humid air. A low morning sun intensivies this happening by nicely illuminating the steam.
I have experienced such a situation at some mornings this week on my way to office. Unfortunately I was sitting in a train and had no camera with me. But I remembered that I had a similar experience during a river cruise some years ago. While browsing my archive I found the photos of that cruise and I was impressed that it was already 7 years ago. Time runs by so fast.
I have taken the photos here on an early, chilly morning in late July 2005 with my Nikon Coolpix E8700 camera from the deck of a cruise ship. They show the steaming river Main near the city of Kelsterbach, Germany.