Physics and Chemistry of Clouds

599 Pages·2011·12.233 MB·English

by  Dennis Lamb

PHYSICS AND CHEMISTRY OF CLOUDS
Cloudsaffectourdailyweatherandplaykeyrolesintheglobalclimate.Throughtheirabil-
itytoprecipitate,cloudsprovidevirtuallyallofthefreshwateronEarthandareacrucial
linkinthehydrologiccycle.Withever-increasingimportancebeingplacedonquantifiable
predictions–fromforecastingthelocalweathertoanticipatingclimatechange–wemust
understandhowcloudsoperateintherealatmosphere,whereinteractionswithnaturaland
anthropogenicpollutantsarecommon.
Thistextbookprovidesstudents–whetherseasonedornewtotheatmosphericsciences–
with a quantitative yet approachable path to learning the inner workings of clouds.
Comprehensive treatments are given of the mechanisms by which cloud droplets form
andgrowonsolubleaerosolparticles,icecrystalsevolveintodiverseshapes,precipitation
developsinwarmandcoldclouds,tracegasesandaerosolparticlesarescavengedfromthe
atmosphere,andelectricalchargeisseparatedinthunderstorms.
Developed over many years of the authors’ teaching at Penn State University, Physics
and Chemistry of Clouds is an invaluable textbook for advanced students in atmospheric
science, meteorology, environmental sciences/engineering, and atmospheric chemistry. It
isalsoausefulreferencetextforresearchersandprofessionals.
DENNIS LAMB is Professor Emeritus of Meteorology at the Pennsylvania State
University. He has been fascinated with clouds ever since growing up in the Midwestern
United States, and the true nature of clouds and the processes that form them have been
graduallyrevealedtohimthroughyearsofformaltrainingandselfstudy.ProfessorLamb
workedasaresearcherfornearly14yearsattheDesertResearchInstitute(Reno)before
embarkingonateachingcareeratPennStateUniversity.Withmorethan40yearsofobser-
vationalandlaboratoryresearchexperience,andmorethan20yearsteachingcloudphysics
andatmosphericchemistryatboththeundergraduateandgraduatelevels,henowrealizes
thatthebestpathtowardunderstandingcloudsistounderstandwateritself,atthemolecu-
larlevel.Thedeepertheunderstanding,thegreaterbecomestheappreciationofcloudsas
gatekeepersinthewatercycleandenergybudgetofEarth.Thisbookistheculmination
ofhiscareerstudyingthephysicsandchemistryofwaterandclouds.
HANS VERLINDE is an Associate Professor of Meteorology at the Pennsylvania State
University.HeisanobservationalmeteorologistwhohasstudiedcloudsintheAntarctic,
at the equator, and in the Arctic. He is currently the site scientist for the US Department
of Energy Atmospheric Radiation Measurement Program Climate Research Facility at
Barrow on the North Slope of Alaska, and he teaches classes in atmospheric thermo-
dynamics, cloud physics, mesoscale meteorology, and radar meteorology at Penn State
University. After a start in meteorology as a weather forecaster, he developed a passion
for clouds, and likes to look at clouds from all sides now, from up and down, from
inside out. He enjoys seeing the surprised looks on student faces when, on the first
day of every semester, he asks “Who can tell me what clouds are in the sky today?”
which inevitably leads to the next question, “Who can tell me what the sky looks like
today?”
PHYSICS AND CHEMISTRY
OF CLOUDS
DENNIS LAMB
PennsylvaniaStateUniversity
JOHANNES VERLINDE
PennsylvaniaStateUniversity
CAMBRIDGE UNIVERSITY PRESS
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(cid:2)c DennisLambandJohannesVerlinde2011
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Firstpublished2011
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Terri,Anneke,Kris,Katrina,andMaarten

Contents
Preface pagexi
PartI Background 1
1 Introduction 3
1.1 Importanceofclouds 3
1.2 Observedcharacteristicsofclouds 5
1.3 Furtherreading 27
1.4 Problems 27
2 Theatmosphericsetting 29
2.1 Composition 29
2.2 Energyintheatmosphere 79
2.3 Structureandorganization 103
2.4 Furtherreading 118
2.5 Problems 119
PartII Transformations 123
3 Equilibria 125
3.1 Molecularinterpretationofequilibrium 126
3.2 Thermodynamicperspectiveofphaseequilibrium 130
3.3 Phaserelationships 132
3.4 Interfaces 139
3.5 Multicomponentsystems 146
3.6 Furtherreading 172
3.7 Problems 172
4 Change 175
4.1 Deviationsfromequilibrium 175
4.2 Ratesofchange 179
4.3 Microscaletransport 183
4.4 Formationofnewsubstances 185
vii
viii Contents
4.5 Aerosolformation 205
4.6 Furtherreading 213
4.7 Problems 214
PartIII Cloudmacrophysics 217
5 Cloudthermodynamics 219
5.1 Overview 219
5.2 Characterizationofamoistatmosphere 219
5.3 Referenceprocesses 222
5.4 Stability 231
5.5 Mixing 235
5.6 Furtherreading 238
5.7 Problems 238
6 Cloudformationandevolution 242
6.1 Coolingmechanisms 242
6.2 Adiabaticsupersaturationdevelopment 247
6.3 Clouddynamics 250
6.4 Mesoscaleorganization 256
6.5 Furtherreading 272
6.6 Problems 272
PartIV Cloudmicrophysics 275
7 Nucleation 277
7.1 Formationoftheliquidphase 279
7.2 Formationofthesolidphase 298
7.3 Furtherreading 318
7.4 Problems 318
8 Growthfromthevapor 320
8.1 Overview 320
8.2 Vapor-growthofindividualliquiddrops 323
8.3 Vapor-growthofindividualicecrystals 342
8.4 Melting 369
8.5 Furtherreading 377
8.6 Problems 378
9 Growthbycollection 380
9.1 Overview 380
9.2 Particlefallspeeds 381
9.3 Collision-coalescence 399
9.4 Riming 407
9.5 Capturenucleation 410
9.6 Aggregation 411
Contents ix
9.7 Furtherreading 413
9.8 Problems 413
PartV Cloud-scaleandpopulationeffects 415
10 Evolutionofsupersaturation 417
10.1 Overview 417
10.2 Extendedtheory 418
10.3 Aerosolinfluences 421
10.4 Quasi-stationarysupersaturation 424
10.5 Microphysicalanddynamicalinfluences 426
10.6 Furtherreading 431
10.7 Problems 431
11 Warmclouds 433
11.1 Overview 433
11.2 Continuouscollection 437
11.3 Diabaticcondensation 439
11.4 Stochasticcollection 440
11.5 Warmrain 445
11.6 Aerosoleffects 452
11.7 Furtherreading 454
11.8 Problems 454
12 Coldclouds 457
12.1 Overview 457
12.2 Iceinitiation 459
12.3 Glaciation 461
12.4 Snowandcoldrain 469
12.5 Hailformationandgrowth 472
12.6 Furtherreading 477
12.7 Problems 477
13 Cloudchemistry 480
13.1 Overview 480
13.2 Scavengingofaerosolparticles 484
13.3 Uptakeoftracegases 500
13.4 Precipitationchemistry 516
13.5 Furtherreading 527
13.6 Problems 527
14 Cloudelectrification 529
14.1 Overview 529
14.2 Macroscalechargeseparation 535
14.3 Microscalechargeseparation 538