ASTRONOMICAL QUANTITIES A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site irradiance Irradiance. Image credit: MIT Also known as radiant flux density, the total energy at all wavelengths falling on a point on a surface from all directions above the surface in a given time. It is measured in watts per square meter (W/m²). See also illuminance. Related category    • ASTRONOMICAL QUANTITIES Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP