With respect to visibility, extinction is the attenuation of light as it passes through medium, such as particulate matter suspended in the air. The attenuation is due to the absorption and scattering of light as it passes through a medium.
Sources: Malm, William C. 1999. Introduction to visibility. Cooperative Institute for Research in the Atmosphere. NPS Visibility Program, Colorado State University, Fort Collins, CO: 79 p. As cited in: Hardy, Colin C., Ottmar, Roger D., Peterson, Janice L., Core, John E., and Seamon, Paula. 2001. Smoke Management Guide for Prescribed and Wildland Fire 2001 Edition. Produced by the National Wildfire coordinating Group Fire Use Working Team.