This crystal ball located outside Darwin Airport Meteorological Office, in Darwin, Australia, doesn’t look into the future, but provides invaluable information about the past. This antique technology, called a Campbell-Stokes sunshine recorder, is one of the simplest meteorological device that’s still in use today. It measures the intensity of sunshine on any given day the same way a thermometer measures temperature or a barometer measures air pressure.
The device consist of a solid glass sphere, typically about 4 inches in diameter, that concentrates the sun's rays to an intense spot on a calibrated paper, resulting in a burn. As the sun blazes across the sky, the hot image of the sun traces a scorching path on the paper. The intensity and the position of the burn indicates the time and the strength of the sunshine.
A Campbell–Stokes sunshine recorder outside Darwin Airport Meteorological Office, in Darwin, Australia. Photo credit: Bidgee/WikimediaRead more »
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