The UVS is a light meter that is sensitive to ultraviolet light. It determines when certain atoms or ions are present, or when certain physical processes are going on. The instrument looks for specific colors of ultraviolet light that certain elements and compounds are known to emit.
The Sun emits a large range of colors of light. If sunlight passes through an atmosphere, certain elements and molecules in the atmosphere will absorb very specific frequencies of light. If the UVS, when looking at filtered sunlight, notices the absence of any of these specific colors, then particulate elements and/or compounds have been detected. This process is call identifying elements or compounds by atomic absorption.
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