How is sea fog formed?

Sea fog is formed under specific ocean hydrological and meteorological conditions. When the lower atmosphere is in a stable state, due to the increase in water vapor and the decrease in temperature, the air near the sea gradually reaches a saturated state. At this time, the water vapor continues to condense into small water droplets, ice crystals, or both with the core of hygroscopic particles such as fine salt particles. The mixture is suspended several meters above the sea surface, tens of meters or even hundreds of meters low in the sky.

Fog is formed when the condensed water droplets increase in size and number, making the sky appear gray-white and further reducing visibility.

When warm, moist air moves over the cold sea surface, the bottom layer cools and water vapor condenses to form advection cooling fog. This type of fog is dense, large-scale, and lasts a long time. It mostly occurs in cold areas. In spring, it is more common in the Thousand Islands in the Pacific and the waters near Newfoundland in the Atlantic. In spring and summer in my country, the sea fog in the East China Sea and Yellow Sea mostly belongs to this type.

The fog generated when cold air flows over the warm sea surface is advective evaporative fog, which mostly appears on the sea surface at high latitudes in the cold season.

Mixed fog is produced by the mixing of two types of air with a large temperature difference and humidity over the ocean.

When storm activity produces air with humidity close to or reaching saturation, it mixes with cold air from high latitudes in the cold season to form cold season mixed fog. In the warm season, it mixes with warm air from lower latitudes to form warm season mixed fog.

When the sea surface is covered with a layer of suspended matter or covered with sea ice, the fog generated by radiation cooling at night is called radiation fog.

Radiation fog mostly appears around dawn and gradually dissipates after sunrise.

On seashores, harbors and high-latitude inland seas, the fog generated by oil pollution or impurities covering the sea surface is called floating film radiation fog; the fog formed on the salt grain layer accumulated at low altitude due to the evaporation of sea water is called floating film radiation fog. It is called salt layer radiation fog; the fog formed on the ice-covered sea surface or huge icebergs at high latitudes is called ice surface radiation fog.

The fog formed by the cooling and condensation of warm and humid air on the sea surface as it climbs toward islands and coasts is called topographic fog. For example, the southeast slope of Mount Laoshan in Qingdao and Mount Putuo in Zhoushan Islands are often shrouded in clouds and fog in spring and summer.

Sea fog