The global cloud cover averages around 0.68 when analysing clouds with optical depth larger than 0.1.
22.
Because optical depth varies with frequency, strength ratios among the hyperfine components differ from that of their intrinsic intensities.
23.
The rings are generally optically thin ( transparent ); their normal optical depths do not exceed 0.1.
24.
The optical depth of the atmosphere is too great for enough of Altair's light to reach the ground.
25.
The power law mentioned above allows estimation of the optical depth and Earth's Moon, 7.4 kg.
26.
Aerosol optical depth at five wavelengths, columnar ozone concentration and surface level size segregated mass concentration of aerosols were carried out.
27.
The optical depth of the atmosphere can be divided into several components, ascribed to Rayleigh scattering, aerosols, and gaseous absorption.
28.
Its average normal optical depth is around 10 " 4, which corresponds to an equivalent depth of 0.4 km.
29.
For the El Chich�n cloud, the optical depth has been measured to be around 0.3 around mid-visible wavelengths.
30.
Optical depth and actual depth, \ tau and z respectively, can vary widely depending on the absorptivity of the astrophysical environment.
