Types of Rain Gauges for Measuring Rainfall | What are Different Types of Rain Gauges
What is Rain Gauge ?
These are the instruments, which is used to measure the amount of precipitation (rainfall) in an area is called rain gauge.
There are two types of Rain Gauges
1. Non-Recording Rain Gauges
2. Recording Rain Gauges
1. Non-Recording Rain Gauge:
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| Symons Rain gauge |
Non-Recording rain gauge is "Symons Rain gauge".
Non-recording type rain gauge is most common type of rain gauge used by the metrological department. It consists of a cylindrical vessel 127mm in diameter with a base enlargement to 210mm diameter.
As it top section, funnel is provided with circular brass rim which is 127mm exactly so that it can fit into vessel well. This funnel shank is inserted in the neck of the base section and thinner than the cylinder, placed into it to receive rainfall.
A receiving bottle has a capacity of 100mm and during heavy rainfall, amount of rain is frequently exceeded, so the reading should be measured 3 to 4 times in a day. water contained in this receiving bottle is measured by a graduated measuring glass with an accuracy up to 0 to 1mm. For uniformity the rainfall is measured every day at 8:0Am IST and it is recorded as a rainfall of the day.
Proper care, maintenance and inspection of rain gauge especially during the dry weather is necessary to keep the instrument free from dust and dirt, so that the readings are accurate.
2. Recording Rain Gauge:
There are three types of recording rain gauges are as follows:
a) Weighing Bucket Type Rain Gauge
b) Tipping Bucket Type Rain Gauge
c) Floating or Natural Syphon Type Rain gauge
a) Weighing Bucket:
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| Weighing Bucket Type Rain Gauge |
The weighing bucket type rain gauge is the most common self-recording rain gauge used in some countries.
It consists of a receiver bucket supported by a spring or lever balance or some other weighing mechanism.
The movement of bucket due to its increasing weight is transmitting to a open which traces record or some marking on a clock driven drum/chart.
The weighing bucket type rain gauge instrument will gives us a plot of the accumulated rainfall values against the elapsed time and the curve so formed is called the mass curve.
b) Tipping Bucket:
It consists of a receiver bucket supported by a spring or lever balance or some other weighing mechanism.
The movement of bucket due to its increasing weight is transmitting to a open which traces record or some marking on a clock driven drum/chart.
The weighing bucket type rain gauge instrument will gives us a plot of the accumulated rainfall values against the elapsed time and the curve so formed is called the mass curve.
b) Tipping Bucket:
Tipping bucket type rain gauge is a 30cm sized circular rain gauge adopted for use by US weather bureau.
It has 30cm diameter sharp edged receiver and at the end of the receiver is provided a funnel.
Tripping bucket completed an electric circuit causing the movement of pen to mark on clock driven receiving drum which carries a recorded sheet.
These electric pulses generated are recorded at the control room far away from the rain gauge stations.
This instrument is further suited for digitalization the output signal.
The pair of buckets are pivoted under this funnel in such a manner that when one bucket receivers 0.25mm of the total precipitation(rainfall), it tips discharging on its rainfall into the container, so bringing the other bucket under the funnel.
c) Floating or Natural syphon type rain gauge:
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| Floating or Natural Syphon Type Rain Gauge |
The working of this type of rain gauge is similar to weighing bucket rain gauge.
A funnel receives the water which is collected in a rectangular container.
A float is provided at the bottom of container, and this float raises as the water level rises in the container.
Its movement being recorded by a pen moving on a recording drum actuated by a clock work.
When the water rises, this float will reaches to the top floating in water, then the syphon comes into operation and then release the water outwards through the connecting pipe, thus all water in the box is drained out.
This rain gauge is adopted as the standard recording rain gauge in India and the curve drawn using this data is known as mass curve of rainfall.
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