There are two fountains like the one pictured above, outside of the building I spend my weekdays in. When the temperature dips below freezing, there is a haze that comes off the fountains (also in the picture above). I assumed they are heated, which seems ridiculous, so I asked the security guard.
Fun and Totally Useless Fact: The fountains are kept at a constant 40 degrees throughout the winter to prevent freezing.
A few years ago, one of the heaters broke and the fountain froze over. The maintenance staff had to go at it with ice picks and carve all the ice out of the fountain. Then they had to carry the blocks of ice and dump them in the street. The next day, 6 of the workers who had to clear out the fountain, quit their jobs.