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Sunshine Recorder
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- 2. Jens Martensson Sunshine Recorder • Asunshine 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. 2
- 3. Jens Martensson • The populartypes of Sunshine Recorder are: 1. Campbell- stokes Recorder 2. Rotating Mirror Sunshine Recorder 3. Blake- Larsen Recorder Types of Sunshine Recorder 3
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- 5. Jens Martensson • It wasinvented 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 5
- 6. Jens Martensson Construction: • It consistsof 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 6
- 7. Jens Martensson Working: • When sunshineis 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 7
- 8. Jens Martensson 8 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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- 10. Jens Martensson • A rotatingmirror 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 10
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- 12. Jens Martensson • Blake-Larsen SunRecorder 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 12
- 13. Jens Martensson Advantages • The systemcan 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 13
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