Abstract: In 2020, the National Natural Science Foundation of China modified the application code of the atmospheric sciences discipline and established 15 secondary disciplines according to the reform needs of the new era. D0505 is one of the secondary application codes for the subdisciplines. This paper introduced the general framework of the secondary application code, its six research directions (boundary layer atmospheric physics and turbulence, cloud and precipitation physics, aerosol physics and aerosol–cloud interactions, atmospheric optics and radiative transfer, atmospheric electricity and acoustics, and physics of the middle atmosphere), and their keywords, as well as the similarities and differences between D0505 and other relevant secondary application codes. The paper then examined possible research patterns and trends by analyzing the publication records under each keyword in different research directions from the Web of Science database in the last five years (2017–2021). This paper will assist fund candidates in correctly selecting application codes, research directions, and keywords.