Low values of the rain wetting sensor

Explanation of the low values of the Rain Moisture Sensor.
Ironically, the fact that a lower wetting value is measured in rain on a scale of 0-20 is due to the nature of water flowing off a sloping smooth surface. The water joins the raindrops into small 'streams' and runs off the surface (cohesive force - attraction of adjacent molecules). The surroundings of the 'rivulets' have a lower physical resistance because water does not stay in these places and therefore the measured value for the whole area is lower in the indicator. The greatest wetting of the leaf in the scale is then achieved during the frost or morning dew, because the entire surface of the leaf is covered with small water droplets that do not combine and do not flow (the cohesive force required to bring the droplets together is weak).

Thus, the dryness indication in the application is 0, the wetness indication is =>1.