We have run into morning fogs from time to time. Sometimes there is just a whisp in the valleys, while other times we hesitate to drive to work because the fog is so thick. Here at the Nature Preserve, the fog makes everything look softer. But what makes the fog?

Fog is considered a low cloud that is either close to ground level or in contact with it. As such, it is made up of water droplets that are in the air like a cloud. Unlike a cloud however, the water vapor in fog comes from sources close to the fog like a large water body or a moist ground. Like a cloud, fog forms when water evaporates from a surface or is added to the air. This evaporation can be from the ocean or another body of water or moist ground like a marsh or a farm field, depending on the type and location of the fog.

As water begins to evaporate from these sources and turn into water vapor it rises into the air. As the water vapor rises, it bonds with aerosols called condensation nuclei (i.e. – small dust particles in the air) to form water droplets. These droplets then condense to form fog when the process occurs close to the ground. It stormed yesterday, so the ground was very soggy today, good conditions for fog formation.

When it’s foggy, it’s great fun to walk around looking at the spider webs, which magically turn into necklaces of diamonds as the water condenses on them. You have to be quick though, because the diamonds disappear when the sun comes out.