How Do You Measure Dew Point And Measure Humidity Percentage?

Humidity is the measure of number of water vapor molecules in atmosphere. There are several ways of expressing it like absolute humidity, or specific humidity, and relative humidity etc. Relative humidity is the ratio of actual amount of water in air to the amount of water which could be held in air in saturated state is called relative humidity. Humidity is measured through dry bulb temperature, which is measured through an ordinary glass thermometer. And through wet bulb temperature, which is measured through a thermometer which is soaked in a wet bag. The wet bulb temperature is less than dry bulb due to cooling effect of the moisture. Once the dry bulb and wet bulb temperatures are known a psychometric chart is used to check the values of relative humidity, which give us the value of relative humidity.

Dew point is the temperature at which the air gets saturated. As we know that all the liquids have a tendency to evaporate or convert them from the liquid phase to the gas phase similarly water also tries to evaporate and enters into atmosphere, however, as water evaporate a certain pressure of vapor is built, with increase in the rate of evaporation the vapor pressure also increases but at a certain pressure air gets saturated and no more evaporation increase in concentration could occur unless this saturation state is changed. Once saturation state is achieved water will condense into dew drops if heat is removed. This dew point temperature could be measured by ordinary thermometers.