A Quick Overview of the Art of Humidity Measurement

WHAT IS HUMIDITY? Humidity is water vapor in air. Water covers over two thirds of the earths surface. It affects everything we do in some way. Under normal atmospheric conditions water is the third largest component of air, but the amount of water in the air can vary widely. These factors make it very important to measure humidity in our environment. Because humidity has always been important many ways have developed to express the level of humidity. Probably the most common is the term RELATIVE HUMIDITY which is based on a combination of humidity and temperature. Terms based on humidity per unit weight or volume are PPM (parts per million), grains per pound, and others. Vapor pressure and dew point are measures of humidity alone. These are all terms used to quantify the question how humid is it