Download Microphysics Lecture Notes #3

OUTLINE
1.  Nucleation of water droplets (6.1)
2.  Microstructures of warm clouds (6.2)
3.  Cloud Liquid Water Content and Entrainment (6.3)
4.  Growth of Water Droplets and Formation of Rain (6.4)
5.  Microphysics of Ice Clouds (6.5)
6.  Cloud Names, Lightning and Chemistry (6.7)
Microphysics of Ice Clouds
Cloudsbelowthe0˚isothermare
referredtoaswarmclouds.
Cloudsabovearecalledcoldclouds.
Microphysics of Ice Clouds
Microphysics of Ice Clouds
Microphysics of Ice Clouds
Microphysics of Ice Clouds
water
WHATARESUPERCOOLEDDROPLETS?
-Liquidwaterthatexistsincloudsattemperaturesbelow0˚C
HOMOGENEOUSNUCLEATIONOFICEPARTICLES
-  ChangeaggregaOonoffrozenwaterleadingtothegrowthofan
icecloudparOcle.Onlywaterispresent.
IcenucleaOonprocesses:
CondensaOon-Freezing:2stepprocess,watervaporcondensesto
formaliquid,thentheliquidfreeze.
DeposiOon:transferofwatervapordirectlytoice
*WewillnotcoverpreacOvaOoninthisclass.Skipfigure6.30.
SaturaOonwithrespecttoliquidvsice
FocusonBlueCurve.
Usey-axisontherighthandside.
Takehomemessage:
es>esi
SecOon6.5.4:FormaOonofprecipitaOonincoldclouds
Cold-rainprocess(Wegener-Bergeron-FindeisenProcess
SupercooledvapordropletsaccumulateonaniceparOclethroughdeposiOon
oppositeofsublimaOon.
subsaturatedenvironmentforliquidwaterbutasupersaturatedenvironmentforice.
AlternatetodeposiOonalgrowth?
RimingandaggregaOon(growthrateincreaseswithsize)
RADARECHOTOMEASURECLOUDMICROPHYSICS
LargeiceparOclesgrow,fall,andmelttoformrain.
OUTLINE
1.  Nucleation of water droplets (6.1)
2.  Microstructures of warm clouds (6.2)
3.  Cloud Liquid Water Content and Entrainment (6.3)
4.  Growth of Water Droplets and Formation of Rain (6.4)
5.  Microphysics of Ice Clouds (6.5)
6.  Cloud Names, Lightning and Chemistry (6.7)
LIGHTNING!
-  Allcloudsallelectrifiedto
somedegree
-  InvigorousconvecOve
clouds,sufficientelectrical
chargesareseparatedto
produceelectricfieldsthat
exceedthedielectric
breakdownofcloudyair,
resulOnginaniniOal
intraclouddischarge.
-  ExactmechanismissOll
debated.Butclearly,
rimersplayarole.
RIMER:graupelorhailstone.
GRAUPEL:snowcrystalcoated
byriming.
LIGHTNING!
Achargemovesup
fromthegroundto
meetthecharge
originaOnginthe
cloud.
LIGHTNING!
Inclassexercise
Separateintogroupsof4
PhaseI:Rapidresponseround
(1minute)
Listinbulletpointsthelifecycleofwatervaporinanairparcelthatendsasrain
ontheground.
PhaseII:Keyfigures
(5minutes)
SketchthekeyfiguresfromtheMicrophysicschapter(labeltheaxes).
PhaseIII:Relaxedresponseround
(5minutes)
Listinbulletpointsthelifecycleofwatervaporinanairparcelthatendsasrain
ontheground.IncludeesOmatesforthesizeoftheliquidparOcle.
CLOUDANDPRECIPITATION
PROCESSESTHATAFFECT
ATMOSPHERICCHEMISTRY