Fog formed over the surface of the ground or water in the event of weather conditions conducive to the condensation of water vapor.However, the mist can be not only a natural phenomenon, but also artificial.Such fog is called radiative cooling due to air under the influence radiatsii.Prirodnye mists thicker than artificial, and their duration ranges from several hours to several days.In effect, a fog - a cloud that is at ground or water.Fogging occurs most often during the night and early morning in low-lying areas, and over the ponds.This is due to the fact that when a cold night or morning air sinks to warm the ground or water, condensed moisture, and a variety of easy water droplets hang in the air.Relative humidity in the location of the mist is close to 100%.Depend
ing on the temperature of mist composition has a different structure.At temperatures above 10 degrees Celsius is a cloud of tiny droplets of water, from -10 to -15 degrees, it is a mixture of water droplets and small ice crystals at temperatures below -15 degrees mist is composed entirely of ice crystals called ledyanym.V communitiespoints fog is denser due to the condensation of water vapor from the exhaust gazov.Po level visibility fog is divided into several types: haze, mist of underground, translucent and dense fog.Haze - it is very foggy.Of underground fog spread along the ground or water, usually a continuous thin layer, and greatly affects the vidimost.Pri translucent fog visibility ranges from a few dozen to several hundred meters, while through it shine sky, clouds, night - the stars and the moon.Sploshnoy mist covers the ground a whitish cloud, through which it is difficult to distinguish between objects and buildings at a distance of several tens of meters.When the fog to clear the air felt damp, it is impossible to see the sky, the clouds, the sun.Obstruct the movement of transport, especially aviation. Fog arises not only when the contact of cold and warm air, and by evaporation, eg, over the sea or wet portion sushi.Suschestvuyut so-called dry fog, which do not consist of water, of smoke, dust and soot.Sometimes the cities there is a mixture of dry and wet fog, for example, due to the release of moist air mass of the particulates smoke or exhaust trubami.Iskusstvenny mist formed by human industrial activity, it is called photochemical smog.It occurs when a variety of atmospheric pollutants, such as products of fuel combustion, gasoline vapors, chemical solvents, paints, pesticides, nitrates and could t.d.Fotohimichesky is one of the most important problems of modern cities.The high content of harmful chemicals in the air leads to poor health, and even death.Particularly affected are children and elderly people with weak immune systems.Prolonged exposure in industrial fog leads to shortness of breath, exacerbation of heart disease, headaches, cough, poisoning and pr.Odnako photochemical smog can occur not only by humans, but also, for example, when a volcanic eruption, when the air there is a large concentration ofsulfur dioxide.