Rainfall recorder (rainfall recorder, or rain gauge, rain gauge), is a meteorologist and hydrologist used to measure a period of time the amount of precipitation in a region of the instrument (snowfall measurements need to use the snow gauge).Commonly, there are two kinds of siphon type and tipping bucket type. on December 18, 1994, China's first optical rain gauge came out.
Framework
A rain gauge is an instrument for measuring precipitation. The rain gauge consists of a water bearer (funnel), a water storage cylinder (outer cylinder), and a water storage bottle with a special measuring cup proportional to its caliber.
Mounting
Placement on a fixed shelf in the observation field.The mouth of the gauge is kept horizontal at a height of 70 centimeters above the ground.In areas where the snow is deep in winter, a backup shelf should be installed near the rain gauge that allows the mouth of the gauge to reach a height of 1.0-1.2 m above the ground.When the snow depth exceeds 30 centimeters, the instrument should be moved to the backup shelf for observation.
For winter snowfall, the funnel must be unscrewed from inside the mouth of the vessel (stations with old rain gauges must change the snow-bearing mouth), remove the water storage bottle, and use the snow-bearing mouth and the water storage cylinder directly to contain the precipitation.
Observation
Most rain gauges measure in millimeters, and sometimes measurements are taken in inches or centimeters.Rain gauge readings can be taken manually or using an automated weather station (AWS), and the frequency of observations can vary depending on the requirements of the collecting unit.In most cases the collected rainwater is not retained after observation, but a few weather stations retain it as a sample for pollution levels or other tests.
Record
There are limitations to rain gauge measurements.It does not make sense to use a rain gauge during excessive winds (tropical storms or hurricanes) because there will be excessive errors in the recorded results while causing damage to the gauge itself.In addition, rainwater adhering to the walls of the barrel or funnel can cause the measurements to be slightly undersized.
Another common problem is that when temperatures are near freezing, rainwater may freeze as it falls on the rain gauge, leading to clogged funnels or other problems.As with other meteorological instruments, rain gauges should be placed in open areas away from buildings and trees to minimize observation errors.
Kind
There are many types of rain gauges, commonly known as siphon rain gauges, weighing rain gauges, tipping bucket rain gauges and so on.
Siphon Rain Gauge
Siphon rain gauge can continuously record the amount of liquid precipitation and the number of hours of precipitation, from the precipitation record can also understand the intensity of precipitation.The siphon rain gauge consists of a water bearer, a float chamber, a self-recording clock and a housing.Rainwater enters the siphon from the topmost siphon opening, is collected in the lower funnel and directed to the float chamber.Float chamber is composed of a cylinder containing floats, floats with the increase of rainwater injection and rise, and drive the self-marking pen rise.The self-registering clock is fixed on the seat plate, and the rotating cylinder is driven by the clock machine to rotate the movement, so that the recording pen draws a curve on the recording paper surrounding the rotating cylinder.
The vertical coordinate on the recording paper records the amount of rain and the horizontal coordinate is driven by a self-registering clock, which indicates the time.When the rainfall reaches a certain height (e.g. 10 mm), the water surface inside the float chamber rises to the siphon pipe connected to the float chamber, causing the siphon to start, rapidly discharging the rainwater inside the float chamber into the storage bottle, while the self-registering pen falls vertically to the zero line position on the recording paper and rises to begin the inflow of rainwater once again, and so on back and forth to continuously record the rainfall process.
Weighing Rain Gauge
This instrument continuously records the weight of precipitation on and stored in the rain catchment cup.The recording method can be by means of a mechanical clockwork device or a balanced hammer system, which records the weight of all precipitation as it falls, and is capable of recording snow, hail, and mixed rain and snow precipitation.
Tipping bucket rain gauge
The tipping bucket rain gauge is a telemetric rainfall instrument composed of sensor and signal recorder, the sensor consists of water bearer, upper tipping bucket, measuring tipping bucket, counting tipping bucket, reed switch and so on; the recorder consists of counter, recorder, self-marking clock, control circuit board and so on.Its working principle is: rainwater from the top of the water bearer into the water bearer, falling into the water funnel, through the funnel mouth into the tipping bucket, when the amount of water reaches a certain height (for example, 0.1 millimeters), the tipping bucket loses its balance and tipping.And every time the dumping bucket dumping, make the switch on the circuit, to the recorder to deliver a pulse signal, the recorder control from the pen to record the rainfall, and so on and so forth can be the rainfall process measurement down.
