1 / 56

Fig. 7-CO, p. 162

Fig. 7-CO, p. 162. Precipitation Processes. SIZES OF: NUCLEI , WATER DROPLETS , and WATER DROPS Factors of 100 X Condensing Nuclei 0.2 m Cloud Droplet 20 m Raindrop 2,000 m. Fig. 7-1, p. 164. Precipitation Processes.

carlos-ruiz
Download Presentation

Fig. 7-CO, p. 162

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fig. 7-CO, p. 162

  2. Precipitation Processes • SIZES OF: NUCLEI, WATER DROPLETS, • and WATER DROPS • Factors of 100 X • Condensing Nuclei 0.2 m • Cloud Droplet 20 m • Raindrop 2,000 m

  3. Fig. 7-1, p. 164

  4. Precipitation Processes • Cloud Droplets -- Form from a condensing nucleus. Droplets form at relative humidity well below 100%, e.g., around 78%. Because many nuclei are hygroscopic (e.g., salt nuclei) there is a reduction of the vapor pressure because of the molecular bond with the water molecule. This reduces the vapor pressure and is called the solute effect.

  5. Precipitation Processes • Cloud droplets are in equilibrium with their environment. There are more molecules surrounding the curved surface because that surface has less surface bonding than a flat surface. Hence the cloud droplet has a higher equilibrium vapor pressure. This is the curvature effect.

  6. Fig. 7-2, p. 165

  7. Precipitation Processes • The region around a cloud droplet is supersaturated so it is above 100% RH. • If the moisture continues (water supply) after condensation the droplet increases, if not it decreases. • Over water (many nuclei) thousands of droplets / cm3 • Over land (fewer nuclei) hundred droplets/cm3

  8. Fig. 7-3, p. 165

  9. Precipitation Processes • Now if the RH increases, the droplets grow because evaporation from the droplet is less than the condensation. • If the air temp cools, then the humidity increases and the droplet grows further.

  10. Precipitation Processes • Falling drop has a terminal velocity • v = 2ga2/(9η) • where a is the droplet diameter, η is the viscosity of air, g = acceleration of gravity • (Above applies to only droplets) • Volume/ air resistance area ratio = 4a/3 • So larger radii drops will fall faster

  11. Table 7-1, p. 166

  12. Collision and Coalescence • In warm clouds (T > -15oC) Collision and Coalescence plays a major role in producing rain drops from cloud droplets. • Ingredients: liquid water content • range of droplet sizes • updrafts of the cloud • electric charge of the droplets • and cloud electric field.

  13. Fig. 7-4, p. 166

  14. Fig. 7-5, p. 167

  15. Bergeron Process • Cold Clouds (T < 15oC) ice-crystal process is the significant process in producing precipitation. • Water droplets are super-cooled and exist down to T = -39oC • At T = -20oC there are more super-cooled water droplets than ice crystals • Nuclei - kaolinite, bacteria (deposition nuclei) and ice crystals (feezing nuclei)

  16. Fig. 7-6, p. 168

  17. Fig. 1, p. 169

  18. Fig. 7-7, p. 169

  19. Fig. 7-8, p. 170

  20. Fig. 7-9, p. 170

  21. Fig. 7-10, p. 171

  22. Fig. 7-11, p. 172

  23. Fig. 7-12, p. 173

  24. Fig. 7-13, p. 173

  25. Fig. 7-14, p. 174

  26. Fig. 2, p. 175

  27. Table 7-2, p. 175

  28. Fig. 7-15, p. 176

  29. Fig. 7-16, p. 176

  30. Table 7-3, p. 176

  31. Fig. 3, p. 177

  32. Fig. 7-17, p. 178

  33. Table 7-4, p. 178

  34. Fig. 4, p. 179

  35. Fig. 7-18, p. 179

  36. Fig. 7-19, p. 180

  37. Fig. 7-20, p. 180

  38. Fig. 7-21, p. 180

  39. Fig. 5, p. 181

  40. Fig. 7-22, p. 181

  41. Fig. 7-23, p. 182

  42. Fig. 7-23a, p. 182

  43. Fig. 7-23b, p. 182

  44. Fig. 7-23c, p. 182

  45. Fig. 7-23d, p. 182

  46. Fig. 7-24, p. 182

  47. Fig. 7-25, p. 182

  48. Fig. 7-26, p. 183

  49. Fig. 7-27, p. 183

  50. Fig. 7-28a, p. 184

More Related