Atmospheric aerosols influence the radiative budget of the earth, and their corresponding forcing strongly depends on the optical properties and vertical distribution. Ground - based remote sensing of aerosols is an ideal for reliable and continuously derives detailed aerosol properties. This book starts with fundamentals of atmospheric aerosols, their composition, residence time, sinks, size distribution, atmospheric radiation interactions, then goes into techniques used for in-situ and remote sensing measurements of aerosols. In addition, a much needed detailed explanation of experimental research work carried out in estimating the aerosol optical depth, black carbon aerosols, vertically resolved extinction coefficient, back scattering coefficient, Particulate depolarization ratios and shortwave radiative properties over a semi - arid region. This information is useful to understand the direct impacts of aerosols on the climate system.