Effect of relative humidity on mixed aerosols in atmosphere

In this study, the effects of relative humidity on the deliquescent point a nd size of internally mixed aerosols diameter, NH4NO3 and (NH4)(2)SO4 were investigated using a Tandem Differential Mobility Analyzer (TDMA) with a re lative humidity conditioner. The growth of mixed aerosols appears to have t wo deliquescent steps. The first one was at about 61.2 similar to 61.3%, bu t the second one was at around 77 similar to 78%. At the first deliquescenc e point, growth ratio at phase change was 7.5%, which agrees with the growt h ratio of ammonium nitrate aerosol. Growth ratio of phase change at the se cond deliquescence point was about 20%, lower than the growth ratio of ammo nium sulfate aerosol. In the relative humidity range of 80 similar to 85%, the growth ratio of the mixed aerosols reached 60%. In other words, it appe ars that growth ratio increases with the size of aerosol. Furthermore, a th eoretical growth model of mixed aerosols was developed and applied to estim ate the amount of composition of the mixed aerosols dissolved at each deliq uescence point. The results also show that some of ammonium sulfate already dissolved at the first deliquescence point according to the theoretical gr owth model.