Why is there fog in the winter?

Condensate is the correct term, Human breath will condense ( for a water vapor) when the outside temperature ( static, not wind chill) is at or below 50 degrees Fahrenheit or l0 degrees centigrade. This is some distance between the freezing point of water, 32 degrees F, or 0 Centigrade. If you can see your breath it is fifty degrees or below this mark. Handy rule of thumb.