1.   If the air temperature and dew point are below freezing, frost may form on the surface, or ice crystals may form in the air.

2.   Local terrain will help determine the distribution of cold air and thus where the frost will form.

3.   Outside, the frost was forming in little sparks on the grass.

4.   The frost would form as the air rushed out and the temperature within plunged, causing water vapor to condense, then crystallize, on the windows.

5.   If the gas were allowed to hover, frost would form on the tank and could turn into dangerous chunks of ice.