 The direct aerosol radiative forcing, DRF, has been estimated for the clear sky conditions over Delhi from January 2006 to January 2007 using Santa Barbara Disorder atmospheric radiative transfer model, SPDART. The single scattering albedo, SSA, and the asymmetry parameter used in this model were estimated using the optical properties of aerosol and cloud, OPAQ model. The annual average AOD observed at 500 nanometers was 0.86 plus or minus 0.42 with an average angstrom exponent 0.68 plus or minus 0.35. The average monthly AOD throughout the year over Delhi was found to be in the range 0.56 to 1.22 with the angstrom exponent in the range 0.38 to 0.96. A high monthly average BC concentration in the range 4 to 15 mu gm minus 3 led to monthly average SSA in the range 0.90 plus or minus 0.4 to 0.74 plus or minus 0.3 during the year. Consequently, the monthly average clear sky D. This article was authored by S. Singh, K. Sony, T. Benu, and others. We are article.tv, links in the description below.