1 Science Intensive Technologies / Naukoemkie tekhnologii (2020), Vol. 21, No. 5, 46-60 Acoustic parameters to get precipitation enhancement inside atmospheric clouds. Tiejian Li, Jiahua Wei, Tamara Tulaikova, Yueyang Chen, Yan Diran, Guoxin Chen, Haitao Ren, Jinzhao Wang, Li Zhang. Tsinghua University, State Key Laboratory of Hydroscience& Engineering, Beijing. 100084, China. Abstract. The article subject tends to precipitation enhancement inside natural clouds through acoustical affect. Two models are analyzed and compared to calculate droplet’s amplitudes during their vibrations inside acoustic waves. The optimal regimes are considered for acoustic impact on natural clouds of different types. A neighboring droplet’s distances in cloud are analyzed depend on cloud parameters of liquid water content and droplets size spectrum including their lognormal size distribution. The minimum level of acoustic energy is indicated for treated cloud to ensure the collision of droplets during their vibration in acoustic field. Additional moderate effect of water vapor condensation on droplets in supersaturated cloud media is considered. Key words: clouds, precipitations enhancement, acoustical wave, lognormal distribution for droplets sizes. 1. Introduction The development of new technical methods and technologies to address the effects produced by climate change [1, 2] is a timely, relevant and challenging task. Time has become now when fresh water is scarce around the world which is one of the associated changes in many natural processes on Earth [3]. The ability to manage an important natural phenomenon such as precipitation is an old dream of mankind [4]. In addition, it is known that many gases and polluted aerosol particles, such as sulfur compounds, dissolving in water [5]. Therefore, new precipitation enhancement methods for natural clouds can also serve as an excellent method of partial removal of man-made pollutants from the atmosphere [6,7]. Traditional methods of precipitation intensification include the effects on convective clouds with hygroscopic [8-11] or ice-forming substances [12-13] which accelerate condensation and increase precipitation. The background is that small cloud carries thousands tons of evaporated moisture and droplets. This is obvious since one of the main cloud parameters is the liquid water content, usually LWC = 0.2 - 2.0 g/m 3 , which is the total mass of droplets in cloud unit. Heavy storm or hail clouds have more water with LWC up to 20 - 30 g/m 3 [10,11]. Typical cloud is several kilometers in height and diameter, so easy estimations indicate there is great water mass in cloud. However no more than 20 - 30% of this amount usually falls in the form of natural precipitation [8]. Therefore, the development of new methods for active effects on clouds or modification of existent methods is necessary. Artificial precipitation is required in agriculture for irrigation in some regions, or extinguishing forest fires etc. Precipitation enhancement can bring cooling and purification for atmosphere, for example, over a large metropolis, which is confirmed