Humidity Humidity Humidity is the amount of water vapour present in air. Water vapour, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. The amount of water vapour needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapour contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 grams of
Vapour density that space. Vapour density Vapour density is the density of a vapour in relation to that of hydrogen. It may be defined as mass of a certain volume of a substance divided by mass of same volume of hydrogen. vapour density = mass of "n" molecules of gas / mass of "n" molecules of hydrogen. Thus: vapour density = molar mass of gas / molar mass of H vapour density = molar mass of gas / 2.016 vapour density = ~½ × molar mass For example, vapour density of mixture of NO and NO is 38. 3.Vapour density is a