Meet snow’s worst enemy – fog
Ever notice when fog is present, snow on the ground takes a serious hit?
It’s not your imagination, and fog doesn’t get the nickname snow-eater for anything. Fog can cut snowbanks down to almost nothing in no time if conditions are right. Here’s how that’s possible.
Remember that fog is just a cloud of tiny water droplets near the ground. It forms when the temperature and dew point approach the same value, either through cooling the air or adding moisture. This causes water vapour to condense into tiny water droplets to form fog.
There are various types of fog based on how it forms and its characteristics, but in the wintertime, we sometimes see the formation of advection fog. That’s when warm, moist air moves over a cooler surface — in this case, snow or ice, and causes the warmer air to be cooled to saturation to form fog.
Even though the initial air mass is being cooled, the process of condensation is a warming process. The release of latent heat during the change from gas to liquid causes the temperature in the environment around the fog to warm.
This warming process then causes snow to melt faster thus, the presence of fog is effective at melting snow. Of course, weather such as warm winds, mild temperatures, rain, and sunshine can also contribute to melting snow, but fog is often most efficient at melting snow during winter.
We’re bound to have some advection fog as spring-like weather makes more appearances, so be sure to watch how fast it can turn a snowy landscape into a grassy one.