Cloud microphysicsClaudia Emde

Meteorological Institute, LMU, Munich, Germany

WS 2011/2012

Introduction Contents References Atmospheric thermodynamics

Cloud formation and cloud dynamics

Cloud movies by B. Mayer

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Introduction Contents References Atmospheric thermodynamics

Cloud types

http://www.wolkenatlas.de/

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Introduction Contents References Atmospheric thermodynamics

Rain drops

Villermaux et al. Nature Physics, 2009Cloud microphysics October 20, 2011 4 / 16

Introduction Contents References Atmospheric thermodynamics

Ice crystals

In situ measurements ofice crystals in a tropicalcirrus cloud

Heymsfield et al., Journal ofAtmospheric Sciences, 2002

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Introduction Contents References Atmospheric thermodynamics

Snow flakes

www.snowflakes.com by K.G. Libbrecht

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Introduction Contents References Atmospheric thermodynamics

Energy balance of the Earth

IPCC report, 2007

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Introduction Contents References Atmospheric thermodynamics

Impact of clouds on climate change

IPCC report 2007Cloud microphysics October 20, 2011 8 / 16

Introduction Contents References Atmospheric thermodynamics

IPCC Bericht 2007

Ringer et al., GRL 2006

“Cloud feedbacks (particularlyfrom low clouds) remain thelargest source of uncertainty.”IPCC Report 2007, Technical Summary

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Introduction Contents References Atmospheric thermodynamics

Overview of cloud physics

Atmospheric thermodynamicsMicrophysics of warm clouds

Nucleation of water vapor by condensationGrowth of cloud droplets in warm clouds (condensation, fall speedof droplets, collection, coalescence)formation of rain

Microphysics of cold cloudshomogeneous nucleationheterogeneous nucleationcontact nucleationcrystal growth (from water phase, riming, aggregation)formation of precipitation

Observation of cloud microphysical propertiesParameterization of clouds in climate and NWP models

Cloud microphysics October 20, 2011 10 / 16

Introduction Contents References Atmospheric thermodynamics

Literature

John M. Wallace and Peter V. Hobbs. Atmospheric Science, Anintroductory survey. Elsevier, 2006.

R. R. Rogers. A short course in cloud physics. Pergamon Press,1976.

Hans R. Pruppacher and James D. Klett. Microphysics of clouds andprecipitation. Springer, 1996.

IPCC. Climate change 2007. Technical report, IntergovernmentalPanel of Global Climate Change, 2007.

Additional publications and slides on website:www.meteo.physik.uni-muenchen.de/~emde/doku.php?id=

teaching:cloud_microphysics:cloud_microphysics

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Introduction Contents References Atmospheric thermodynamics

Exam

Written exam in last week of semester: 9th February 2012, 14-16 h

Please let me know if date is inconvenient!

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Introduction Contents References Atmospheric thermodynamics

Gas laws and the ideal gas equation

Sir Robort Boyle (1627–1691) Jacques Charles (1746–1823)

pV = mRT pα = RT pV = nR∗T p = n0kT

John Dalton(1766–1844)

Amedeo Avogadro(1776–1856)

Ludwig Boltzmann(1844–1906)Images from Wikipedia

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Introduction Contents References Atmospheric thermodynamics

The hydrostatic equation

Figure from Wallace and Hobbs

∂ p∂ z

= −gρ gdz = −αdp

Sir Issac Newton (1642–1727)Image from Wikipedia

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Introduction Contents References Atmospheric thermodynamics

First law of thermodynamics

Figure from Wallace and Hobbs

energy conservation

dq = du + dwdq = du + pdαdq = cpdT − αdp· · ·

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Introduction Contents References Atmospheric thermodynamics

Adiabatic processes

adiabatic = change in physical state without heat exchange⇒ dq = 0

Figure from Wallace and Hobbs

dq = du + pdα

T rises in adiabaticcompressionT=const. in isothermalprocess

TC > TB ⇒ pC > pB

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