HazeWert
HazeWert is a meteorological index used to quantify the haziness of the lower atmosphere at a given location and time. It serves as a simple, comparative measure that can reflect changes in aerosol content, humidity, and air quality that influence light scattering and visibility.
The term combines haze with Wert, a German word for value, and has appeared in European meteorology
A common approach defines HazeWert as the ratio of diffuse horizontal irradiance to global horizontal irradiance
Measurements come from ground-based instruments such as sun photometers and pyranometers, and can also be inferred
Limitations include sensitivity to solar geometry, local calibration, and the influence of humidity and surface conditions.