Weather Basics - How Fog Affects Sailing

• Radiation Fog
  This is formed after sunset in clear conditions. The rapid cooling of land produces condensation of air by radiating its heat upwards. As the air in contact with the land cools, the water vapor condenses which creates Fog.Radiation Fog does not last long until sunrise because as the land heats up, the air gets warmer and dew point increases. However, do not be complacent when dealing with it. Cloudy days can make it longer for the land to heat up, thus, Fog will not disperse quickly.


• Advection Fog
  Advection is the process of transporting moist, warm air over cool water. When this happens, it cools down and then the water vapor condenses into Fog called Advection Fog. Dry Wind is needed in order for the Advection Fog to disappear. Otherwise, this will bring problems to sailors.


• Frontal Fog
  Also called Precipitation Fog, Frontal Fog forms when warm, moist air rises over cooler air. The water vapor cools below its dew point, forming Fog which can obscure landmarks. In this condition, navigators will find it difficult to do their Pilotage work.


• Steam Fog
  Usually formed in Polar Regions, Steam Fog is similar to smoke or steam. This is produced when cold air passes over warmer water. It absorbs and condenses water vapor as the dew point is reached.