About Sunshine Cards
Sunshine Cards are used with a Campbell-Stokes type Sunshine Recorder. The Campbell Stokes sunshine recorder consists essentially of a glass sphere mounted concentrically in a section of a spherical bowl, the diameter of which is such that the sun’s rays are focused sharply on the sunshine card held in grooves in the bowl, leaving burn patterns on the sunshine card.
As the earth rotates the position of the burn spot moves across the sunshine card. When the sun is obscured the trace is interrupted. These sunshine cards are marked with hourly intervals. The paper used in these sunshine cards is a special kind, such that the cards char rather than burn. Three overlapping pairs of grooves are provided in the spherical segment so that the sunshine cards can be suitable for different seasons of the year (one pair for both equinoxes), their length and shape being selected to suit the geometrical optics of the system. Different sunshine cards are used in different seasons.
We have sunshine recorder cards available in various designs to suit a wide variety of manufacturers for the Campbell-Stokes Recorder.