Often, especially in autumn and winter, fogs appear over the surface of the land, rivers, seas. They can be completely invisible, and so dense that it is difficult to see through them.
Instructions
Step 1
Fog is an atmospheric phenomenon characterized by the formation of a stratus cloud on the earth's surface. It consists of tiny water droplets or ice crystals.
Step 2
Fogs are of several types. It depends on the processes underlying their formation and on the locality where they occur. Fog can be radiation, advective, and frontal.
Step 3
Radiation fog has nothing to do with harmful radiation. Its second name is "surface". The lower surface air layer rapidly cools as a result of heat exchange with the ground. Thus, the warmer air rises higher. If the weather is calm, then this atmospheric phenomenon either does not occur at all, or is expressed very weakly. When the wind is light, the formation of fog is more intense. If the wind gusts are strong, then it dissipates, because layers of air are mixed.
Step 4
Most often, radiation fog occurs in autumn and winter, when there is high relative humidity and long nights. It also appears in the centers of high pressure areas, which are usually characterized by light winds and no precipitation. Occurring in the evening or at night, such fog can persist throughout the day if the air is relatively stable.
Step 5
Advective fog is formed over terrain, the temperature of which is lower than the air temperature above it. In this case, the air is quickly cooled, a rapid process of steam condensation begins. A thick and low fog appears. In other words, vapor becomes saturated in the lower atmosphere, and a layered cloud of considerable vertical extent forms near the earth's surface. Advective fog can form at any time of the day. Most often it occurs on the sea coasts, as well as in areas partially covered with snow. In temperate latitudes, such fog can form when warm southern air masses are transported north. Advective fog is a frequent visitor over the open sea. It arises from the movement of warm air over the colder sea surface. Sea fogs can be lingering. Sometimes they do not dissipate for weeks.
Step 6
Frontal fogs arise from the interaction of two air masses with different properties. The meeting place is called frontal zones or fronts. Such areas are often found in the atmosphere, but not all of them are accompanied by fogs. More often, frontal fog can be observed in front of a warm front. Accompanied by precipitation, it can be quite long. Frontal fogs are very dangerous for all modes of transport, especially air traffic.
Step 7
Fogs in metropolitan areas, mixing with smoke and exhaust gases, pose a huge danger to human health, especially for those who suffer from cardiovascular diseases and respiratory diseases. In addition, fogs in large industrial areas show how polluted the air is: smog prevents the natural drop in air temperature at night.
