Done by :Girish Raghunathan (1459409)

SUNSHINE RECORDING

SUNSHINE RECORER• A sunshine recorder is a device that records the amount of sunshine at a given location. The results provide information about the weather and climate as well as the temperature of a geographical area. This information is useful in meteorology, science, agriculture, tourism, and other fields. It has also been called a heliograph.

• The popular types of sunshine recorder are :1)Campbell-Stokes Recorder2)Blake-Larsen Recorder

Campbell Stokes Recorder• The Campbell–Stokes recorder (sometimes called a Stokes sphere) is a kind of sunshine recorder. It was invented by John Francis Campbell in 1853 and modified in 1879 by Sir George Gabriel Stokes. The original design by Campbell consisted of a glass sphere set into a wooden bowl with the sun burning a trace on the bowl

Fig. Campbell Recorder in 1853

Fig. Improved design of Campbell recorder by Sir George Stokes

• Stokes's refinement was to make the housing out of metal and to have a card holder set behind the sphere.

Working• The hours of bright sunshine are recorded by the rays of the sun passing through the sphere, which undergo focus and burn a hole through the card placed behind it.  The card itself is calibrated so that the hours and minutes of the day are measured across it.  At dawn and dusk, however, the sun will usually leave a scorch mark rather than a burn and so the readings at those times of day are somewhat difficult to read at times.  

Fig. Sunshine record cards

Blake Larsen Recorder

Fig. Inventor Alan Blake with the recorder

Blake Larsen RecorderDesigned a few years ago , the Blake Larsen Sunshine Recorder is a more sophisticated sunshine recorder that uses sensors to detect solar radiation and record them.The recorder unit and PC software produce a fully automated system to measure the duration of bright sunlight from dawn to dusk.The system will be very easy to integrate into WEB based weather recording systems as the sun shine records are simple text files.It will also produce sun shine reports including graphical presentation to a central WEB server and all the installation sites will be available worldwide using Google Earth .

Blake Larsen RecorderThe main advantages of this are :The system can produce results which are far more accurate than, the Campbell Stokes recorder which requires manual intervention and skilled interpretation. The typical application areas – besides amateur weather enthusiast of course – could be:1)Holiday resorts who wants to prove their claim of sunny days2)Agriculture to establish figures for moisture evaporation which are dependent on actual sun shine hours.3)Feasibility of establishing solar energy – water heating and/or photovoltaic panels.

Blake Larsen Recorder

Fig. Blake Larsen Recorder