"m " is the " optical mass " or " airmass factor ", a term approximately equal ( for small and moderate values of " ? " ) to 1 / cos " ? ", where " ? " is the observed object's optical thickness, which is necessary for the correction of satellite images and also important in accounting for the role of aerosols in climate.
22.
In physics, "'optical depth "'or "'optical thickness "', is the " natural logarithm " of the ratio of incident to " transmitted " radiant power through a material, and "'spectral optical depth "'or "'spectral optical thickness "'is the natural logarithm of the ratio of incident to " transmitted " dimensionless, and in particular is not a length, though it is a monotonically increasing function of path length, and approaches zero as the path length approaches zero.
23.
In physics, "'optical depth "'or "'optical thickness "', is the " natural logarithm " of the ratio of incident to " transmitted " radiant power through a material, and "'spectral optical depth "'or "'spectral optical thickness "'is the natural logarithm of the ratio of incident to " transmitted " dimensionless, and in particular is not a length, though it is a monotonically increasing function of path length, and approaches zero as the path length approaches zero.
