An overview on quantitative characteristics (quantum yield, action spectrum, maximum amount of photoadsorbed molecules) of photoadsorption and photocatalytic processes on some metal oxides, which are main components of the tropospheric solid aerosols, is presented. For the example of MgO, it is shown that the quantitative characteristics of photoadsorption of freons obtained for the air-exposed MgO samples are significantly different from that obtained for the samples experiencing a rigid pretreatment.It is supposed that a sensitization of insulator oxides to the solar radiation spectrum in the troposphere may be due to the formation of an adlayer on their surface under conditions of the Earth's atmosphere.