Airborne Laser Scanning (ALS) has been used extensively to collect dense clouds of terrain and feature points to generate accurate Digital Elevation Models (DEMs) and feature databases. To enable the use of an ALS-based terrain navigation system for autonomous aircraft navigation, continuous availability of the system must be ensured. The most important factor affecting the availability and reliable operation of ALS-based systems are weather effects. Weather conditions like fog, cloud cover, rain, and snow affect the availability, continuity and accuracy of the system when used for navigation purposes. This thesis focuses on the scattering of light by atmospheric particulates and its effects on the ALS ranging and target detection. It discusses the phenomenon of light scattering, important relations concerning ALS and laser ranging, the theories and equations governing it. Data were collected under various weather conditions with an experimental ALS setup at the Ohio University airport, Albany, OH. The processed data helped us analyze the intensity variation with range, thus serving as a performance characterization tool for the ALS system, enabling performance analysis of ALS-based terrain navigators.