Fabry Quantifies Ozone in the Upper Atmosphere (Great Events from History II: Science and Technology Series)
Article abstract: Fabry determined the amount of ozone in an atmospheric column, leading to discovery of the ozone layer.
Summary of Event
Experiments performed in the eighteenth century showed that air is a mixture composed of different substances, rather than being a single element as long supposed. Early study of the major, reactive gases of the atmosphere—oxygen, nitrogen, and carbon dioxide—was followed by investigations of other components.
Ozone is a notable gas because of its sharp odor. Impure ozone is produced easily by a spark in oxygen and can collect in the atmosphere near large electric motors. Curious about the possible concentration of ozone at the earth’s surface, Walter Noel Hartley devised chemical procedures for collecting and testing for ozone in the laboratory in 1881. Since the concentration of ozone is extremely low, the volume of air required for such tests is large. Thus, Hartley needed to apply spectroscopy to detect ozone in the higher atmosphere.
The science of spectroscopy was at an early stage of development in the late nineteenth and early twentieth centuries. There were no good light detectors other than photographic film. Though film images were all black and white, people recognized that the dispersion of light into different colors caused by a prism made the different colors fall onto different places on a film. The relative attenuation of light at each...
(The entire section is 2391 words.)
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