- It is an indicator of the amount of water vapor in air
- Its is divided into absolute and relative humidity.
- Mass of water vapor present in unit volume of air is called absolute humidity.
- Ratio of mass of water vapor present in certain volume of air and mass of water vapor required to saturated it at same condition.
- where m= mass of water vapor present and M is mass of water vapor required to saturated.
- Is is unit less quantity.
- It is the temperature at which the water vapor present in air is just sufficient to saturated it.
- The vapor pressure at room temperature is equal to the saturated vapor pressure at dew point
- Mass of water vapor present in atmosphere is directly proportional to saturated vapor pressure (svp).
- where, p is svp at dew point and P is SVP at room temperature
RH = %
The negative slope of the fusion curve indicates that the melting point of ice decrease with increase of pressure