It is the lightest and most abundant chemical element in the universe. The study of the waters of the Earth, especially with relation to the effects of precipitation and evaporation on the occurrence and character of water in lakes, rivers and below the land surface. It includes atmospheric water, surface water and ground water. An instrument that measures the water vapor content of air. Having a chemical affinity for water.
Hygroscopic substances absorb water well before the relative humidity reaches saturation.
Airborne particles that act as condensation nuclei are usually hygroscopic. A fall in body temperature below the usual level, occurring when the body fails to maintain adequate production of heat during conditions of extreme cold and very rapid heat loss. This leads to progressive slowing of body functions.