Forms Of Condensation
The deposition of water vapour in the form of tiny droplets on the colder bodies by condensation is known as dew. The clear sky, absence of wind. The object on which dew forms must be good radiator and bad conductor are necessary conditions for formation of dew.
When the temperature of air falls below 00 C before the dew point is reached, the water vapour is directly converted into crystals of ice, and this is called as frost. It is frequently called as a form of sublimation, Forts is injurious to vegetation.
Extremely small water droplets suspending in the atmosphere and reducing the horizontal visibility is fog.
Conditions necessary for formation of Fog:
i) The ground should not get much heated during daytime.
ii) The air must not be very dry
iii) Wind velocity should be calm or less the 3 mph.
iv) Inversion, radiation or cold mass advection must takes place.
Classification of Fog:
A) Thick Fog : Restricts visibility up to 45 meters
B) Moderate Fog : Restricts visibility up to 450 meters
C) Thin Fog : Restricts visibility up to 900 meters.
Mist is less dense fog. The suspended water droplets restrict Visibility between 1000 to 2000 meters or 4 on the coded scale (IMD) The obscurity is known as mist. Relative humidity is at least 75% Mist disappears with rising sun.
It is formed when wet fog having super cooled droplets immediately freeze on striking objects like telegraph post having temperature below freezing point. White ice is formed on windward side.
The combined effect of smoke and fog droplets may reduce visibility and this phenomenon is called smog.
Some solid particles like dust, smoke from fire and industry restrict visibility is haze.