LWS Leaf Wetness Sensor

This sensor detects water (dew, rain, or snow) on surfaces using a resistance grid.  It is intended to be a surrogate for a leaf to indicate when the leaf surface is wet.  ISFS uses it primarily for quality control to indicate when radiometers might have rain or snow on their optics, indicating that their readings may not be realistic. For this reason, ISFS ingests the data for this sensor only through a spare analog input in our NR01 radiometers.

This sensor just reports voltage, but the character of changes in this voltage can be interpreted to determine what type of water was present.  A dry sensor has a constant low voltage.  Rain often is indicated by a sudden increase in voltage with large variations.  Dew is a slow increase in voltage overnight, followed by a sharp drop in the early morning.  Snow appears similar to dew, but with an onset at any time of day and no drop at dawn.  Knowledge of the water type can be useful for other purposes.