Out of the Lab and Into the Air: Peter Hobbs and the Physics and Dynamics of Real Clouds

1. Out of the Lab and Into the Air:Peter Hobbs and the Physics and Dynamics of Real Clouds Robert A. Houze, Jr. University of Washington, Seattle, WA Peter V. Hobbs Symposium, New Orleans, January 24, 2008

2. Mason’s Influence

3. The Physics of Clouds Sir John Mason, D. Sc., F. R. S. Preface to 1957 Edition: “Although the emphasis here is on themicro-physicalprocesses, it is important to recognize that these are largely controlled by the atmospheric motions which are manifest in clouds. These macro-physical features…might more properly be called a dynamics…Progress in cloud physics has been hindered by a poor appreciation of these interrelations between processes ranging from nucleation phenomena on the molecular scale to the dynamics of extensive cloud systems on the scale of hundreds or thousands of kilometres. “…Because I am convinced that future progress will be largely governed by our improved understanding of cloud dynamics, I hope that the next few years will see a greatly increased effort in this direction…Cloud dynamics will, I hope …form the subject of a separate volume…” B. J. M., London

4. The Physics of Clouds Sir John Mason, D. Sc., F. R. S. Preface to 1971 Edition: “…in the preceding preface written thirteen years ago, reference was made to the…importance of acquiring a much deeper understanding of the cloud dynamics…The hopes expressed then for much greater effort and progress in this direction, and for the appearance of a major text on this aspect of the subject, have yet to be realized…” B. J. M., Bracknell

5. Peter at his desk, 1973

6. Getting out of the lab and into the clouds by going to the top of a mountain, 1966 We need a bigger plane…

7. Getting out of the lab and into the clouds by buying an airplane, the B-23 in 1968

8. Peter’s Love Affair with Ice

9. Peter’s Opus, 1974

10. Mountainside Aircraft Hobbs (1973) Aggregates in the real atmosphere

11. Rimed & Unrimed Aggregates Graupel Hobbs (1973) Fall velocities of real ice particles

12. Ice Particle Concentrations in the Real Atmosphere

13. Hobbs (1969) Measurements on Mt. Olympus 104 103 Ratio of particles to ice nuclei 102 10 –2 –14 –26 Estimated Cloud Top Temperature (ºC)

14. 104 103 102 Maximum ice particle Concentration (per liter) 101 10 10-1 Cloud Top Temperature (ºC) Hobbs (1976) Measurements aboard the B-23

15. Hobbs and Rangno (1985) Aircraft measurements in various midlatitude clouds

16. Rangno and Hobbs (2005) Measurements in tropical convective clouds over the West Pacific Largest ice concentration ever observed by Peter ~1000 per liter

17. Ice Particles in Relation to Cloud Macro-structure

18. Matejka, Houze, and Hobb(1980) Frontal Clouds

19. Hobbs and Rangno (1985) Midlatitude Cumulonimbus

20. Hobbs and Rangno (1985) Development of Stratus

21. Peter Hobbs: Radar Pioneer?

22. 1973

23. Warm advection seen by color display of NCAR CP-3 radar deployed in Washington CYCLES PROJECT Use of Single-Doppler Color Display Baynton, Serafin, Frush, Gray, Hobbs, Houze, Locatelli (1977)

24. 9 mm cloud radar reflectivity showing fallstreaks in a warm frontal zone e from soundings CYCLES PROJECT Locatelli and Hobbs (1987)

25. IMPROVE Project 2001 NCAR S-Pol on a mountain and NOAA S-Prof in a valley

26. IMPROVE Project Woods, Stoelinga, Locatelli, and Hobbs (2005)

27. IMPROVE Project Woods, Stoelinga, Locatelli, and Hobbs (2005)

28. IMPROVE Project Fearless, no-holds-barred-science

29. LEGACY • Characteristics of ice particles in real precipitating clouds (fallspeeds, aggregation,…) • High ice particle concentrations (negates the importance of the “ice crystal process” as a precipitation mechanism) • Ice particle concentrations and characteristics in relation to “macro-structure” of real of clouds (stratus to convection, tropics to arctic, over oceans, land, and mountains)

30. Peter Hobbs 1936-2005