The research on atmospheric aerosols and other minor constituents was initiated as a well-focused theme during the diversification of the research activities prior to the formation of SPL from the erstwhile SPD, as early as 1982. Under this, indigenous experiments were conceived and developed to characterize the atmospheric the minor constituents and to study their radiative/environmental impacts. The theme of aerosol studies was brought under the Aerosols and Atmospheric Lasers (AAL) Branch of SPL with the thrust area being in-house development of experimental tools particularly active techniques like lidars. The first lidar probing of atmosphere was realized in India with the CWL (Continuous Wave Lidar) becoming operational in early 1983. It was a spectacular view to see a green streak of laser light going through the air in the early night, attracting the curiosity of several, and inviting queries from agencies such as the civil aviation. For the first time in India, a monostatic pulsed Ruby Lidar system was developed for investigations of the tropospheric and stratospheric aerosols. In-house developed Multi-Wavelength solar Radiometer (MWR) got commissioned in 1985 for the estimation of aerosol spectral optical depths. With a view to provide a thrust to scientific research on aerosols, ATmospheric Aerosols (ATA) Branch has been formed by 1996. Later, the ATA branch broadened its activities by undertaking challenging demands from the areas of radiation, microwave remote sensing, cloud studies, lidar based probing of the atmosphere aerosol chemistry and atmospheric trace gases of climatic and environmental significance. In view of the diverse areas of activities undertaken by this group, a new branch - AACCR (Atmospheric Aerosols, Chemistry, Clouds and Radiation) - emerged by 2006. A state of the art Micro pulse lidar became operational for altitude profiling of aerosols. A network of MWR stations was established covering various geographic/climatic zones over India. Aiming at focused research on Chemical Characterisation of Aerosols and Trace Gases, a new branch of activity on Aerosol Chemistry and Trace Gases (ACTG) has been carved out of AACCR in 2014.