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Hand
Anemometer |
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The
Hand Anemometer is a small portable instrument that gives a
direct reading of wind speed.
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instrument is held up to the wind away from obstruction. A vertical
spindle with three small plastic cups rotates on ball bearings
at a rate proportional to the wind speed. A permanent annular
(ring-shaped) magnet is affixed to the lower end of the spindle.
As the spindle rotates, the rotation of the radial magnetic
field induces currents in a metal cylinder inside the body of
the instrument. The resultant deflection is approximately |
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proportional
to the wind speed. The speed is indicated by the position of
two red pointers against a fixed scale engraved on the transparent
outer casing of the instrument. |
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Sunshine
Recorder |
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The
[Campbell-Stokes Pattern] Sunshine Recorder is used to measure
the duration of sunshine, that is, the number of hours of sunshine
per day.
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sun’s rays are focused by a glass sphere to an intense spot
which will char a mark on a curved, specially designed card
mounted concentrically with the sphere. As the earth rotates,
the position of the spot moves across the card leaving a measurable
trace. Due to changing cloud cover or the occurrence of precipitation, |
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the
trace may not necessarily be continuous. At the end of the day,
the total length of the trace is proportional to the duration
of sunshine. |
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Rain
Gauge |
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The
Rainfall Gauge is used to measure the amount of rainfall over
a specified area.
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rainfall gauge has a collecting funnel at its entrance, which
is designed to minimize the loss of rain by splashing. The rain
falls through an aperture at the base of the funnel into a collecting
jar, which is seated inside an inner can to collect any overflow.
The rainfall is then measured, usually once per day, by pouring
the collected rainfall into a separate measuring jar. |
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The
base of the gauge is splayed outwards at the bottom to provide
additional stability. |
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