1. Chapter 5: Cloud development and precipitation Atmospheric Stability Atmospheric Stability Determining stability Determining stability Cloud development and stability Cloud development and stability Precipitation processes Precipitation processes Precipitation types Precipitation types Measuring precipitation Measuring precipitation

2. Atmospheric stability

3. stable and unstable equilibria stable and unstable equilibria air parcels air parcels adiabatic process adiabatic process adiabatic lapse rates adiabatic lapse rates Stability does not control whether air will rise or sink. Rather, it controls whether rising air will continue to rise or whether sinking air will continue to sink Stability does not control whether air will rise or sink. Rather, it controls whether rising air will continue to rise or whether sinking air will continue to sink

4. Determining stability

5. A stable atmosphere environmental lapse rate environmental lapse rate absolute stability absolute stability stabilizing processes stabilizing processes subsidence inversions subsidence inversions stable air provides excellent conditions for high pollution levels stable air provides excellent conditions for high pollution levels

6. An unstable atmosphere absolute instability absolute instability warming of surface air warming of surface air destabilizing processes destabilizing processes superadiabatic lapse rates superadiabatic lapse rates unstable air tends to be well-mixed unstable air tends to be well-mixed

7. Conditionally unstable air conditional instability conditional instability dry and moist adiabatic lapse rates dry and moist adiabatic lapse rates

8. Cloud development and stability

9. surface heating and free convection surface heating and free convection uplift along topography uplift along topography widespread ascent widespread ascent lifting along weather fronts lifting along weather fronts

10. Convection and clouds thermals thermals fair weather cumulus fair weather cumulus fair weather cumulus provide a visual marker of thermals fair weather cumulus provide a visual marker of thermals bases of fair-weather cumulus clouds marks the lifting condensation level, the level at which rising air first becomes saturated bases of fair-weather cumulus clouds marks the lifting condensation level, the level at which rising air first becomes saturated

11. Topography and clouds orographic uplift orographic uplift rain shadow rain shadow The rain shadow works for snow too. Due to frequent westerly winds, the western slope of the Rocky Mountains receives much more precipitation than the eastern slope. The rain shadow works for snow too. Due to frequent westerly winds, the western slope of the Rocky Mountains receives much more precipitation than the eastern slope.

12. Precipitation processes

13. Collision and coalescence process terminal velocity terminal velocity coalescence coalescence warm clouds warm clouds A typical cloud droplet falls at a rate of 1 centimeter per second. At this rate it would take 46 hours to fall one mile. A typical cloud droplet falls at a rate of 1 centimeter per second. At this rate it would take 46 hours to fall one mile.

14. Ice crystal process cold clouds cold clouds supercooled water droplets supercooled water droplets saturation vapor pressures over liquid water and ice saturation vapor pressures over liquid water and ice accretion accretion The upper portions of summer thunderstorms are cold clouds! The upper portions of summer thunderstorms are cold clouds!

15. Cloud seeding and precipitation cloud seeding cloud seeding silver iodide silver iodide It is very difficult to determine whether a cloud seeding attempt is successful. How would you know whether the cloud would have resulted in precipitation if it hadn’t been seeded? It is very difficult to determine whether a cloud seeding attempt is successful. How would you know whether the cloud would have resulted in precipitation if it hadn’t been seeded?

16. Precipitation in clouds accretion accretion ice crystal process ice crystal process

17. Precipitation types

18. Rain rain rain drizzle drizzle virga virga shower shower Virga is much more commonly observed in the western US, because the humid climate of the eastern US reduces the visibility. Virga is much more commonly observed in the western US, because the humid climate of the eastern US reduces the visibility.

19. Snow snow snow fallstreaks fallstreaks dendrite dendrite blizzard blizzard Snowflake shape depends on both temperature and relative humidity Snowflake shape depends on both temperature and relative humidity

20. Sleet and freezing rain sleet sleet freezing rain freezing rain rime rime Sleet makes a ‘tap tap’ sound when falling on glass Sleet makes a ‘tap tap’ sound when falling on glass

21. Snow grains and snow pellets snow grains snow grains snow pellets snow pellets graupel graupel

22. Hail updraft cycles updraft cycles accretion accretion a hailstone can be sliced open to reveal accretion rings, one for each updraft cycle a hailstone can be sliced open to reveal accretion rings, one for each updraft cycle

23. Measuring precipitation

24. Instruments standard rain gauge standard rain gauge tipping bucket rain gauge tipping bucket rain gauge It is difficult to capture rain in a bucket when the wind is blowing strongly It is difficult to capture rain in a bucket when the wind is blowing strongly

25. Doppler radar and precipitation radar radar Doppler radar Doppler radar