Rain Gauge
(LIQUID
PRECIPITATION ACCUMULATION SENSOR)
The
Liquid Precipitation Accumulation Sensor (Rain Gauge) measures the amount
of liquid precipitation. The precipitation accumulation sensor is a heated
tipping bucket rain gauge.
The Rain Gauge is a free-standing receptacle for measuring precipitation. It contains an open top, which measures approximately one foot in diameter. The sensor allows precipitation to fall into the upper portion, which is called the collector. The collector is heated to melt any frozen precipitation, such as snow or hail, for collection. Collected water is funneled to a mechanical device (tipping bucket), which incrementally measures the accumulation and causes the momentary closure of a switch for each increment. The tipping bucket is designed to measure in increments of 0.01 inch of rain. As water is collected, the tipping bucket fills to the point where it tips over. This action empties the bucket in preparation for additional measurements, closes the momentary switch, and signals another 0.01 inch of precipitation to the Data Collection Package (DCP). Water discharged by the tipping bucket passes out of the rain gauge through a lower funnel to the ground below.
At specified sites, a 48-inch diameter wind shield is installed around the rain gauge. The wind shield reduces wind updrafts and wind streamlines that alter rain trajectories.