Hallet-Mossop Process as a Mechanism for Ice Multiplication

Report
Hallet-Mossop Process as a
Mechanism for Ice Multiplication
Steven Brown
Atmospheric Sciences
5/16/2011
Outline
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Role of Ice Particles in precipitation
Evidence for Ice Multiplication
What is the Hallet-Mossop Process?
Initial Experiment
Additional Parameterizations
Conclusion
Motivation
• ICE is complicated:
diverse morphologies,
shapes and sizes
• Influences: radiation
feedback, cloud
formation, precipitation,
etc.
• Better understanding of
ice in atmosphere >better understanding of
dynamics of atmsphere
Ice Formation
• Ice formed via
▫ Homogeneous nucleation
 No nuclei present
 At temperatures <-34°C
▫ Heterogeneous nucleation
 Nuclei are present
 Best nuclei: size, in-soluble,
similar lattice structure
Heterogeneous nucleation of
supercooled liquid water
drops
http://youtu.be/O0uwGlgkgfY
Evidence for Ice Multiplication
Fletcher-Ice Nuclei Curve
 = (1 − )
Meyes –Ice Nuclei Curve
 = exp[ + [100 ∗ ( -1)]]
Hobbs, V. P. (1968). Ice Multiplication in
Clouds. Journal of the Atmospheric
Sciences, 315-318.
• No one-to-one relation between ice nuclei and
ice particle concentration
• Must be secondary process for ice crystal
formation
• -Ice Multiplication
Hallet Mossop Process
Hallett, J., & Mossop, S. C. (1974, May 3).
Production of secondary ice particles
during the riming process. Nature, 249,
26-28.
Hallet Mossop Process
Hallet-Mossop Process
Parameterization
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Environmental Temperature range -3°C to -9°C
Droplets radius >20m
Rimer Temperature range -3°C to -9°C
Estimated 300 splinters ejected per cm^3 rime
accreated
Conclusions
• Hallet-Mossop process best candidate for Ice
Multiplication Mechanism
• More work to be done:
▫ Correlate with droplet size, fall speed, rimer size
▫ Develop theoretical explanation of mechanism
• Better understanding of process->better
understanding of microphysical properties of
clouds
Bibliography
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Supercooled Water Droplets. (2011, January 11). Retrieved May 8, 2011, from SkyLibary:
http://www.skybrary.aero/index.php/Supercooled_Water_Droplets
Barrel, J. A. (n.d.).
Choularton, T. W. (1978, August 24). A Possible Mechanism of Ice Splinter Production During Riming. Nature, 274, 791-792.
Connolly, P. J. (2006, May 5). Modeling the influence of rimer surface temperature on the glaciation of intense thunderstorms; The Rime-Splinter
Mechanism of Ice Multiplication. Quarterly Journal of the Roal Meteorological Society, 132, 3059-3077.
Griggs, D. J., & Choularton, T. W. (1983, January). Freezing modes of riming droplets with application to ice splinter production. Quarterly Journal of
the Royal Meteorological Society, 109(459), 243-253.
Hallett, J., & Mossop, S. C. (1974, May 3). Production of secondary ice particles during the riming process. Nature, 249, 26-28.
Heymsfield, A. J., & Mossop, S. C. (1984). Temperature depedence of secondary ice crystal production during soft hail growth by riming. Quarterly
Journal of the Royal Meteorological Society(110), 765-770.
Hobbs, V. P. (1968). Ice Multiplication in Clouds. Journal of the Atmospheric Sciences, 315-318.
King, W. D., & Fletcher, H. D. (1976). Thermal Shock as an Ice Multiplication Mechanism. Journal of Atmospheric Sciences, 85-96.
Mossop, S. C. (1985, March 1985). The Origin and Concentraion of Ice Crystals in Clouds. American Meteorological Society, 66(3), 264-273.
Pitter, R. L., & Pruppacher, H. R. (1973). Awind tunnel investigation of reezig of small water drops falling at terminal velocity in air. Quarterly Journal
of Meteorological Sciences(99), 540-550.
Pruppacher, H. R., & Klett, D. J. (1997). Microphysics of Clouds and Precipitation. New York: Kluwer Academic Publishers.
Pruppacher, H. R., & Klett, J. D. (1975). A wind tunnel inverstigation on ice multiplication by freezing of water drops falling at terminal velocity in air.
Geophysical Research Letters, 80, 380-381.
Rangno, A. L. (2008, April). Fragmentation of Freezing Drops in Shallow Maritime Frontal Clouds. American Meteorological Society, 65, 1455-1466.
Strangeways, I. (2007). Cloud droplets, ice particles and precipitation . In I. Strangeways, Precipitation: Theory, Measurement and Distribution (pp.
106-118). Cambridge : Cambridge University Press.
Wallace, J. M., & Hobbs, P. V. (2006). Atmospheric Science: An Introductory Survey. London: Academic Press.

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