attenuation

1. (Also called extinction, especially in reference to optical frequencies.) A general term used to denote a decrease in signal strength in transmission from one point to another.

For the propagation of electromagnetic waves through a medium, attenuation is caused by absorption and scattering. The volume attenuation coefficient (m⁻¹) of such a medium is the fractional reduction of radiance per unit pathlength. In radar usage, the specific attenuation is the fractional reduction in power density per unit pathlength as plane-wave radiation propagates through a medium, usually expressed in decibels per kilometer. Attenuation ordinarily does not refer to the inverse-square falloff of irradiance or power density with range that is simply a consequence of beam divergence.
See extinction coefficient.

1. The scattering and absorption of radiant energy by clouds or the atmosphere that decreases the radiation received by satellite sensors.

1. (Also called extinction, especially in reference to optical frequencies.) A general term used to denote a decrease in signal strength in transmission from one point to another.