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7: Precipitation Processes

  • Page ID
    46094
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    Alison Nugent and David DeCou

    Learning Objectives

    By the end of this chapter, you should be able to:

    • Recall the importance of cloud condensation nuclei and aerosols
    • Calculate the speed of a falling cloud droplet and raindrop
    • Describe the Collision-Coalescence process
    • Describe the Ice Phase (Wegener-Bergeron-Findeisen) process

    • 7.1: Introduction
      This page explains the differences in formation and size between cloud droplets and raindrops, highlighting that cloud droplets average 20 micrometers while raindrops are about 2 millimeters. It emphasizes that condensation is not enough for rain and discusses size limits imposed by surface tension and air friction. The key distinction is the fall velocity, with larger droplets being significantly affected by gravity.
    • 7.2: Cloud Droplets
      This page covers the processes of cloud droplet and raindrop formation, highlighting the importance of cloud condensation nuclei (CCNs) and two main precipitation theories: collision-coalescence in warm clouds and the ice phase process in cold clouds. It also discusses ice crystal formation mechanisms, including homogeneous and contact freezing. The Wegener-Bergeron-Findeisen process illustrates the growth of ice crystals by utilizing surrounding liquid droplets.
    • 7.3: Precipitation Types
      This page discusses the ice phase process in global precipitation, detailing types such as rain, snow, sleet, and hail, all influenced by environmental conditions and the journey of ice crystals. It explains how variations in temperature and air mass interactions determine the type of precipitation. Subsequent chapters will delve deeper into these atmospheric dynamics.


    7: Precipitation Processes is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.