Question

explain the following:
- absolute humidity
-relative humidity
-dew point

Answer 1

Absolute humidity is the amount of water vapor in a unit volume of air which is expressed in kilograms per cubic meter. It does not change according to the temperature of the air. When there is a high amount of water vapor in the air, absolute humidity will also be high.
Relative humidity is the percentage or ratio of the amount of water vapor in a volume of air at a given temperature and the amount that it can hold at that given temperature. An amount of water vapor in warm air will result to a lower relative humidity than in cool air.
When the relative humidity is high, the evaporation of the moisture of the skin is reduced and decreases the effectiveness of sweating in cooling the body. The heat index which is used during the summer is used to measure this effect. It is not only influenced by temperature but also by the air’s moisture content or absolute humidity and the saturated vapor pressure. It is used in circumstances wherein the rate of water evaporation is necessary.
The dew point is the temperature to which airmust be cooled to become saturated with water vapor. When further cooled, the airborne water vapor will condense to form liquid water 

Answer 2

$\LARGE{ \underline{\underline{\sf{Relative\: humidity:}}}}$

The ratio between the amount of water vapour present in the atmosphere and the total water holding capacity of the atmosphere at a given temperature is called relative humidity . It is usually expressed in percentage . If the absolute humidity is half of the total water holding capacity at a particular temperature , then the realtive humidity will be 50%. It is measured using an instrument called wet and dry bulb thermometer .

$\LARGE{ \underline{\underline{\sf{Absolute\: humidity:}}}}$

The actual amount of water vapour present in the atmosphere is called absolute humidity . It is measured as the amount of water vapour present per cubic metre volume of air (g/m³) .

$\LARGE{ \underline{\underline{\sf{Humidity:}}}}$

The water content in. the atmosphere is called humidity

$\LARGE{ \underline{\underline{\sf{Dew\: point:}}}}$

The critical temperature at which condensation begins is called dew point