Dry, cracked skin. Chapped lips. Static electricity. Wisconsin’s winters are extremely dry, and if you don’t have any way to increase the humidity in your home, the weather will literally suck the moisture right out of you. You need humidity.
Humidity is a measure of the amount of water vapor in the air. There are three primary measurements of humidity: absolute, relative and specific. Absolute humidity is the actual water content of air at a given temperature expressed in weight/volume. Relative humidity, expressed as a percent, measures the current absolute humidity relative to the maximum humidity for that temperature. Specific humidity, sometimes referred to as the humidity ratio, is the ratio of the mass of water vapor to total mass of the air sample.
Humans are sensitive to humidity because our bodies use evaporative cooling as the primary mechanism to regulate body temperature. The rate at which preparation evaporates off the skin is lower under humid conditions than it would be under dry conditions. This is why we feel warmer when the relative humidity is higher than when it is lower, even at the same temperature.