Aerosol optical depth

From Glossary of Meteorology

aerosol optical depth

The optical depth due to extinction by the aerosol component of the atmosphere.

Aerosol optical depths typically decrease with increasing wavelength and are much smaller for longwave radiation than for shortwave radiation. Values vary widely depending on atmospheric conditions, but are typically in the range 0.02–0.2 for visible radiation.
See also turbidity.

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