Most scientists are in opinion that rain drops form taking available dust particles or bacteria as nucleus present in atmosphere. What is wrong in thinking that the dust particles & bacteria as stated get attached to rain drops during horizontal and vertical movement of rain drops in atmosphere?
There is nothing wrong with your statement. In fact the droplets start to grow by both homogeneous and heterogeneous nucleation with the later being much more effective (by the several orders of magnitude). When the droplets grow further due to the condensation process they start to absorb small particles (which acted previously as the condensation nuclei) in the process known as in-cloud scavenging. It is convenient, therefore to look at small dry particles and droplets as two coupled aerosol systems.
Thank you, Sir Janusz for your answer.Sir, I focus on first a tiny rain droplet to take its shape at starting point. After a drop of smallest rain forms, it grows then in numerous ways and techniques, we study how it gets its first shape?
Most scientists are in opinion that rain drops form taking available dust particles or bacteria as nucleus present in atmosphere. What is wrong in thinking that the dust particles & bacteria as stated get attached to rain drops during horizontal and vertical movement of rain drops in atmosphere? As such rain drops clean our atmosphere making it dust free,odor free and bacteria free due to excellent properties of water.
Dear Radhashyam,
We should distinguish between the cloud droplets and rain droplets. First we observe the growth of cloud droplets following the heterogeneous nucleation, after this, they start to remove some of the small particles due to in-cloud scavenging. The rain droplets are formed later on and they are not very effective in removing very small particles because the hydrodynamic forces push them away from the large falling droplets of rain. The entire process is well described in the book by Prupacher and Klett: Microphysics of Clouds and Precipitation.
Regards,
Janusz
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