How does radiation fog occur and what are the conditions for its formation?

2020-11-17 2020-11-17T16:20:59Z

ArabiaWeather - We always hear about fog, but have you ever known that fog has types? Fog has more than one type and they are radiation fog, rising fog, frozen fog, evaporation fog, valley fog, and traveling fog. Today, we will show you how radiation fog occurs and the conditions for its formation.<h2 style=";text-align:left;direction:ltr"> How does radiation fog happen?</h2> Radiation fog occurs at night (or it occurs at the end of the night and the beginning of the day in the early morning hours) above the surface of the earth when the earth loses its heat by radiation and cools, and thus the air in contact with it cools, and in the event that water vapor is available and the air temperature reaches the dew point or below it, the radiation fog is formed . With the condition that the wind speed is light and not static, so that the warmer air is allowed to pass over the cold surface and touch it, and thus it cools to or below the degree of dew. But if the air is static, then only the lower part of the warmer air near the surface of the earth is the one that touches the cold surface of the earth, and in this case condensation occurs in a thin layer that may reach 60 cm from the surface of the earth, and here a fog may form in contact with the surface of the earth in a thin layer very. Or it may condense and form dew or frost (depending on the temperature)<h2 style=";text-align:left;direction:ltr"> Conditions for the formation of radiation fog:</h2> Light winds: wind speeds between 1-5 knots (about 8 km / h). High humidity up to 100% A clear sky where the clouds deserted the sky: (Long clear nights, so that there would be enough time for the air to cool down to the point of dew). Therefore, radiation fog usually occurs during the winter season and in late autumn and early spring.<h2 style=";text-align:left;direction:ltr"> How does radiation fog fade?</h2> It fades by heating by the sun's rays , as the radiation fog fades within several hours after sunrise, after the sun heats the air and the surface of the earth, and sometimes the fog is dense, blocking the sun's rays from reaching the surface of the earth, and thus the surface of the earth remains cool, and usually This condition occurs in the winter and fog can remain throughout the day. Increase wind speed : If the wind speed exceeds 8 km / h, this prevents the occurrence of radioactive fog or causes its fading, because it works to mix the cold surface air with the warmer and less humid air above it, and this prevents the air near the surface of the earth from dropping the degree Its temperature is dewy, and even if the state reaches dew and fogs , the air will work to quickly evaporate the fog. Heating by descending air. Changing the direction and blowing of the winds from a new source. Radiation fog is common and well-known and forms on flat ground in wet and clear nights, and is usually associated with high pressure situations. But if the wind speed is higher than 15 knots and with an air turbulence, this works to mix the air and often the fog rises up forming very low stratified clouds, and transitional fog can form very quickly during the day or night, and it is common in winter, when Air masses move to land from the seas and oceans.

This article was written originally in Arabic and is translated using a 3rd party automated service. ArabiaWeather is not responsible for any grammatical errors whatsoever.

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