Here's how a sunshine recorder works:
1. Focal Point: The recorder consists of a glass sphere, typically made of high-quality optical glass. This glass sphere acts as a converging lens, focusing the sun's rays to a point called the focal point.
2. Spherical Bulb and Stand: The glass sphere is mounted on a sturdy stand, usually made of metal. The stand positions the sphere in a way that its focal point falls on a specially designed card held in a frame.
3. Record Card: The card used in the recorder is made of a material that is sensitive to heat or ultraviolet (UV) radiation. The card is marked with a scale that indicates hours of the day and may have additional markings for recording the date, location, and other relevant information.
4. Focusing: The position of the glass sphere is carefully adjusted to ensure that the sun's rays are focused accurately onto the card. This ensures a precise record of the duration of sunshine.
5. Burning Effect: When the sun shines, its concentrated rays at the focal point burn a trace on the card. This trace is caused by the heat or UV radiation generated by the focused sunlight.
6. Recording: As the sun moves across the sky, the focal point moves accordingly, and the burn mark traces a path on the card. The length and position of this trace indicate the duration and time of sunshine throughout the day.
7. Measuring Sunshine Duration: By comparing the burn mark on the card with the markings indicating hours on the scale, the total duration of sunshine for the day can be measured.
8. Data Collection: The recorded cards are collected and analyzed to determine the daily sunshine hours at a particular location. These measurements contribute to climatological data and studies related to solar radiation, weather patterns, and climate change.
It's important to note that sunshine recorders are not dependent on electricity and rely solely on the burning effect of focused sunlight to record sunshine duration. They provide a straightforward and reliable method for monitoring the amount of sunshine at a particular location.