The Hail Harp sensor was developed in a partnership between the German Meteorological Service (DWD) and Eigenbrodt GmbH & Co KG. The patented measuring principle allows the reliable detection of small and large hailstones and effectively distinguishes these hail events from all other forms of precipitation. The Hail Harp can be used in a standalone configuration, when only the hail information is relevant. It is also useful as an add-on for plausibility checks of present weather sensors, which often provide erroneous hail information.
In contrast to other known hail sensors, the Hail Harp’s unique detection surface is composed of parallel metal strings instead of a closed surface. Only hail stones of 4mm diameter or larger have enough momentum to move the strings. These movements are picked up by a contactless transducer and the output signal allows a distinction between large and small hail.