Fog

Who would have thought that there would be so many types of fog? Today we were learning about a few.

• Radiation Fog, caused by the ground cooling (by radiation) under humid air at night, common around estuaries in the autumn.
• Advection Fog, well known in San Fransisco where warm air meets the cold Labrador currents, caused when warm air travels horizontally (advects) over a cold surface causing it to reach its dewpoint. This fog is common at sea in Spring and early Summer when the sea is at its coldest.
• Sea Smoke occurs when very cold air meets a relatively warm sea. If the air is 9°C cooler than the water the water will begin to evaporate.
• Hill Fog - not really fog but stratus cloud formed by the adiabatic cooling of humid air as it rises up the hill.
• Valley Fog is caused by katabaic winds (which flow downhill and are cold) flowing into the valley and is a form of Radiation Fog.
• Mixing Fog is caused when different air masses meet.
• Frontal Fog occurs at the passage of a warm front or an occluded front. The air masses mix in the frontal zone and the mixture becomes saturated.

Who would have thought that there were so many different types of fog. I'm sure that even this list is not exhaustive. It reminds me of the Eskimos and all their different words for snow. I quite like meteorology, it seems to be the most scientific of all the subjects I'm studying.