A sunshine recorder is a device that records the amount of sunshine at a given location at any time.The popular types of Sunshine Recorder are:
Campbell- stokes Recorder
Rotating Mirror Sunshine Recorder
Blake- Larsen Recorder
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Sunshine Recorder
• A sunshine recorder is a device that
records the amount of sunshine at a
given location at any time.
• The results provide information
about the weather and climate as
well as the temperature of a
geographical area.
• This information is useful
in metrology, science, agriculture,
tourism and other fields.
• It has also been called a heliograph.
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Martensson
• The popular types of Sunshine Recorder are:
1. Campbell- stokes Recorder
2. Rotating Mirror Sunshine Recorder
3. Blake- Larsen Recorder
Types of Sunshine Recorder
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• It was invented by John Francis
Campbell in 1853 and modified in 1879
by Sir George Gabriel Stokes.
PRINCIPLE:
• It concentrates sunlight through a glass
sphere onto a recording card placed at
its focal point.
• The length of the burn trace left on the
card represents the sunshine duration.
Campbell- Stokes Recorder
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Construction:
• It consists of a glass sphere mounted
concentrically in a section of a spherical
bowl.
• The diameter of the bowl is such that
the sun rays are focused sharply on a
card held in grooves in the bowl.
Campbell- Stokes Recorder
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Working:
• When sunshine is present the glass
ball would focus the rays and burn a
hole through a strip of photosensitive
card. As the sun moves across the sky
a corresponding hole would be made
in the card.
• Different shaped strips of card are
used to account for the change in the
Sun’s position in the sky throughout
the year. Typically 3 shapes are
available.
• At the end of each day, the card
would be removed. The reader would
measure the burn holes. The length of
the holes made in the card would
indicate duration.
Campbell- Stokes Recorder
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Campbell- Stokes Recorder
• The major advantage of this type of
recorder is its simplicity and ease of use.
• There are no moving parts and it thus
requires very little maintenance.
Disadvantages
• Rain may cause the card to be torn
when removing it and thus making it
difficult to read.
• It is also susceptible to external, non-
weather factors such as dust, dirt or
dried bird droppings accumulating on
the glass sphere which requires frequent
inspection and cleaning.
Advantages
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• A rotating mirror is used to reflect
sunlight onto the photo sensor, and the
occurrence of sunshine is detected by
measuring the intensity of the light
received.
• The rotating mirror rotates once every
30 seconds.
• Once the instrument is set to an angle
corresponding to the latitude at the site
by adjusting the scale on the body at
installation, the double-surfaced mirror
reflects sunlight as required throughout
the year regardless of changes in the
sun’s elevation.
Rotating Mirror Sunshine Recorder
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• Blake-Larsen Sun Recorder was
developed by Alan Blake (UK) and Ole
Jul Larsen (Denmark).
PRINCIPLE
• It detects sunshine duration as the
human eye would do by its design and
measuring principle.
• Light, reflected by the dome, passes
through a special filter unto the LUX-
sensor. (can separately measure infrared,
full-spectrum or human-visible light.)
• A scientifically deduced algorithm then
determines whether the sun is shining
or not.
Blake- Larsen Recorder
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Advantages
• The system can produce results which
are far more accurate than, for example,
the Campbell Stokes recorder which
requires manual intervention and skilled
interpretation.
• It will also be much more affordable
than the methods used by professional
forecasters yet will give comparable
results.
Blake- Larsen Recorder
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