Meteorological instruments -- Measurement of Precipitation
Tipping Bucket Rain-gauge
The tipping bucket rain-gauge is commonly used for measuring rainfall at automatic weather stations. The rain-gauge comprises of a divided bucket assembly, which is pivoted at its centre like a seesaw. Rain collects in the upper half of the bucket, which is adjusted to tilt when a predetermined amount of water has been collected. The tilting action discharges the collected water, and re-positions the opposite half under the discharge nozzle ready for filling. At the same time, the tilting action also generates an electric pulse which can be monitored by a data logger and totalled over selected time periods to provide rainfall amount.
The rain-gauge with the bucket size to collect the accumulated precipitation of 0.5 mm to cause one tilt is used in the Hong Kong Observatory.
Rainfall data recorded from these rain-gauges at outstations can be readily telemetered to the Observatory Headquarters via telephone lines. Rainfall readings at 5-minute intervals are available from different locations in the territory. These rain-gauges record rainfall amount in units of 0.5 mm.