author = "Braga, Ramon Campos and Rosenfeld, Daniel and Weigel, Ralf and 
                         Jurkat, Tina and Andreae, Meinrat O. and Wendisch, Manfred and 
                         P{\"o}schl, Ulrich and Voigt, Christiane and Mahnke, Christoph 
                         and Borrmann, Stephan and Albrecht, Rachel I. and Molleker, Sergej 
                         and Vila, Daniel Alejandro and Machado, Luiz Augusto Toledo and 
                         Grulich, Lucas",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {The Hebrew 
                         University of Jerusalem} and {Johannes Gutenberg-Universit{\"a}t} 
                         and {Institut f{\"u}r Physik der Atmosph{\"a}re} and {Max Planck 
                         Institute for Chemistry} and {Universit{\"a}t Leipzig} and {Max 
                         Planck Institute for Chemistry} and {Johannes 
                         Gutenberg-Universit{\"a}t} and {Johannes 
                         Gutenberg-Universit{\"a}t} and {Johannes 
                         Gutenberg-Universit{\"a}t} and {Universidade de S{\~a}o Paulo 
                         (USP)} and {Max Planck Institute for Chemistry} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Johannes 
                title = "Aerosol concentrations determine the height of warm rain and ice 
                         initiation in convective clouds over the Amazon basin",
              journal = "Atmospheric Chemistry and Physics Discussion",
                 year = "2017",
               volume = "2017",
                pages = "1--44",
             abstract = "We have investigated how pollution aerosols affect the height 
                         above cloud base of rain and ice hydrometeor initiation and the 
                         subsequent vertical evolution of cloud droplet size and number 
                         concentrations in growing convective cumulus. For this purpose we 
                         used in-situ data of hydrometeor size distributions measured with 
                         instruments mounted on HALO (High Altitude and Long Range Research 
                         Aircraft) during the ACRIDICON-CHUVA campaign over the Amazon 
                         during September 2014. The results show that the height of rain 
                         initiation by collision and coalescence processes (Dr, in units of 
                         meters above cloud base) is linearly correlated with the number 
                         concentration of droplets (Nd in cm-3) nucleated at cloud base (Dr 
                         \≈ 5ĚNd). When Nd exceeded values of about 1000 cm-3, Dr 
                         became greater than 5000 m, and particles of precipitation size 
                         were initiated as ice hydrometeors. Therefore, no liquid water 
                         raindrops were observed within growing convective cumulus during 
                         polluted conditions. Furthermore, also the formation of ice 
                         particles took place at higher altitudes in the clouds in polluted 
                         conditions, because the resulting smaller cloud droplets froze at 
                         colder temperatures compared to the larger drops in the unpolluted 
                         cases. The measured vertical profiles of droplet effective radius 
                         (re) were close to those estimated by assuming adiabatic 
                         conditions (rea), supporting the hypothesis that the entrainment 
                         and mixing of air into convective clouds is almost completely 
                         inhomogeneous. Secondary nucleation of droplets on aerosol 
                         particles from biomass burning and air pollution reduced re below 
                         rea, which further inhibited the formation of raindrops and ice 
                         particles and resulted in even higher altitudes for rain and ice 
                  doi = "10.5194/acp-2016-1155",
                  url = "http://dx.doi.org/10.5194/acp-2016-1155",
                 issn = "1680-7367",
                label = "lattes: 5379515759830546 14 BragaRWJAWPVMBAMVMG:2017:AeCoDe",
             language = "en",
           targetfile = "braga_aerosol.pdf",
        urlaccessdate = "15 abr. 2021"