2. RAIN GAUGE
A rain gauge is an artifact used in
meteorological stations to help
measure and collect precipitations
that fall in a certain place.
Precipitations are all hydrometeor
falling to the earth from the
atmosphere, including rain, drizzle,
hail, snow and sleet, fog etc.
There are two types of rain gauges,
non-recording type and recording
type.
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3. NON-RECORDING TYPE RAIN-GAUGE:
It gives only total rainfall occurred during particular
time period.
most commonly used type is Symon’s rain-gauge.
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4. SYMON‘S RAIN GAUGE
It gives the total rainfall that
has occurred at a particular
period.
It essentially consists of a
circular collecting area 127
mm in diameter connected to
a funnel.
The funnel discharges the
rainfall into a receiving vessel.
The funnel and the receiving
vessel are housed in a
metallic container.
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5. RECORDING TYPE RAIN GAUGES
These are rain gauges which can give a permanent,
automatic rainfall record in the form of a pen mounted
on a clock driven chart.
From the chart intensity or rate of rainfall in cm per
hour or 6 hrs, 12 hrs and total amount of rainfall can
be obtained.
There are three types of recording rain gauges
Weighing bucket type
Tipping bucket type
Floating or natural syphon type rain gauge
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6. ADVANTAGES OF RECORDING RAIN GAUGES
Necessity of an attendant does not arise
Intensity of rainfall at anytime as well as total rainfall is
obtained,
Data from in accessible places can be continuously
obtained once gauge is
established.
Human errors are eliminated.
Capacity of gauges is large.
Time intervals are also recorded.
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7. DISADVANTAGES OF RECORDING RAIN GAUGES
High initial investment cost.
Recording is not reliable when faults in gauge arise
(mechanical or electrical) till faults are corrected.
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8. WEIGHING BUCKET TYPE RAIN GAUGE
It is most common self-recording rain gauge.
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
transmitted to a pen which traces record or some
marking on a clock driven chart.
The instrument gives a plot of the accumulated rainfall
values against the elapsed time and the curve so
formed is called the mass curve.
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10. TIPPING BUCKET TYPE RAIN GAUGE
It 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.
Pair of buckets are pivoted under this funnel in such a
manner that when one bucket receives 0.25mm of
precipitation it tips discharging its rainfall into the
container, bringing the other bucket under the funnel.
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11. tipping of bucket completes 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 station.
This instrument is further suited for digitalizing the
output signal.
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13. 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.
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14. When water rises, syphon releases the water
outwards through the connecting pipe, thus all
water in box is drained out.
This rain gauge is adopted as the standard
recording rain gauge in India.
curve drawn using this data is known as mass
curve of rain fall.
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