The Texas Electronics, Inc. TR-525USW Rainfall Sensor with 8" diameter funnel is a remote tipping bucket style rain gauge that measures liquid precipitation.
The Rain Gauge is a freestanding receptacle for measuring precipitation. Through an opening at the top of the device, rain is collected and then funneled to a mechanical device, called a tipping bucket. As water is collected, the tipping bucket fills to the point that it tips over, causing a momentary closure of a switch to incrementally measure rainfall accumulation. This action empties the bucket in preparation for additional measurement. Water discharged by the tipping bucket passes out of the rain gauge with no need for emptying.
The TR-525USW is specifically designed to meet the National Weather Service's requirements for rainfall measurement.