The Davis 6420 Leaf Wetness Sensor for use with wireless Temperature, Leaf Wetness and Soil Moisture monitoring station.
The leaf wetness sensor is used to detect the presence of surface moisture on foliage and calculate the duration of wetness. When moisture is present, the sensor detects an electrical resistance change between the gold-plated elements of the grid.
When used with a Vantage Pro2 with Wireless Leaf & Soil Moisture / Temperature Station, or the EnviroMonitor system this is reported as a value between 0 (dry) and 15 (wet).