(a) Why is the air in a region dry?
(b) How is humidity measured? (c)what are the prerequisites for condensation?
Answers
Answer:
(a) The air in a place can be dry due to the minimum amount of water vapour present in the atmosphere due to less evaporation. For eg: Rajasthan lies in a region with dry and hot air. There is hardly any moisture in the air.
(b) Humidity of the air is measured in grams per cubic meter. When the humidity in the air is 0 gm/cu.m., the air is said to be dry. If the humidity in the air at 30° C temperature is 37 gms/ cu.m., then the air is said to be saturated.
(C)The process of changing water vapour in the air into water is called condensation. If the temperature of the air reduces, its vapour holding capacity also reduces. When relative humidity of the air becomes 100%, vapour starts condensing. At this time, the temperature of the air should be at dewpoint. It implies that for condensation, temperature should be low and relative humidity must be high. In the free environment, condensation of the vapour in the air occurs around fine particles (dust, salt, etc.) in the air. Dew, frost and fog are the forms of condensation at ground level while clouds are a form of condensation at higher elevation.
Answer:
1 : - The air in a region is dry primarily due to low moisture content. Moreover,distance from the sea ,the high speed of the wind and increased rate of evaporation contribute to a decrease in the moisture holding capacity at the atmosphere.
2:-humidity is the measure of the amount of moisture in the air.A psychrometer uses two thermometers to measure relative humidity.
3:-the only requirement for condensation are moist air and a cool surface. In the winter,the moisture content of the indoor air.