Mauna Loa sky conditions - Bench mark and present

Sky conditions at the Mauna Loa Solar Observatory (MLSO) were measured during a period of uncontaminated skies in July 1981, and during the presence of volcanic dust clouds in 1982 using MLSO instrument systems. A six-fold increase in scattering due to aerosols, is accompanied by a 25 percent direct incident radiation decrease, and sky polarization/intensity perturbations were detected after the onset of volcanic clouds.