|MadSci Network: Earth Sciences|
The water was "steaming" because it was "relatively" hot compared to its surroundings. When the water was warmer than the very cool air, there was enough of a temperature difference to produce "steam" [droplets of water that condense in the cooler air].
While we often think of steam from only hot water, it is actually the difference in temperature from water to air that helps water to evaporate. Although a bit technical, here is a good discussion:
Water can also boil and produce steam at cooler temperatures if the pressure is
lowered in a vacuum. See this link:
The following answers in our archives may also be helpful - you may want to read through them with your mom if they cover things you haven't yet had in school:
Try the links in the MadSci Library for more information on Earth Sciences.