produced at taxedo.com U.S. Standard Atmosphere 1976
Pressure [mbar] 10-4 10-3 10-2 10-1 1 10 102 103 110
100
90
80
70
60
50 Altitude [km] 40
30 P 20
10
0 U.S. Standard Atmosphere 1976
Pressure [mbar] 10-4 10-3 10-2 10-1 1 10 102 103 110 110
100 Thermosphere 100
90 90 Mesopause 80 80
70 Mesosphere 70
60 60
50 Stratopause 50 Altitude [km] 40 40 ozone 30 T Stratosphere 30 layer P 20 20
10 Tropopause 10 Troposphere 'weather' 0 0 180 200 220 240 260 280 300 Temperature [K] To a good approximation air can be treated as an ideal gas!
Dalton's law:
Mixing ratio: diffusion constant for inert species! important => "heterosphere" ~mesopause
80
HO2 CO2 Ar O2 N2 60
well-mixed 40 => "homosphere" Altitude (km)
highly variable! 20 removal of water by precipitation! 0 -6 -5 -4 -3 -2 -1 0 10 10 10 10 10 10 10 Mixing ratio (mol/mol)
adapted with changes from Bohren, Huffman and Clothiaux, 2010 as well as from Roedel and Wagner, 2011 'Janus' behavior of water
Water is the most effective greenhouse gas! => heating!
The Earth with clouds
Robert A. Rohde, globalwarmingart.com: Atmospheric Transmission.png
Water is also the greatest reflector of incoming sunlight => cooling Water cycle: ¤ dominant source: ¤ evaporation and evapotranspiration
¤ total atmospheric water mass: ~1.3x1016 kg
¤ loss rate: ¤ global mean precipitation rate is ~1000 mm per year =ˆ ~5.1x1017 kg/year
¤ mean atmospheric lifetime of a water molecule:
total mass = H2O loss rate
1.3x1016 kg = 5.1x1017 kg/year
= ~9 days! Other functions of water:
¤ energy transport (latent heat) => enhances vertical mixing of air
¤ cleansing agent for water-soluble trace gases ¤ cleansing agent for aerosol particles
¤ catalyst for heterogeneous chemical reactions => e.g. ozone hole chemistry 110 Thermosphere 100 90 80 70 Mesosphere 60 50
40
30 Stratosphere Altitude (km)
20 equatorial
10 polar Troposphere
0 100 150 200 250 300 350 Temperature (K) fog
110 Thermosphere 100 90 80 wikimedia.org: fog.jpg 70 Mesosphere 60 50
40
30 Stratosphere Altitude (km)
20 equatorial
10 polar Troposphere fog 0 100 150 200 250 300 350 Temperature (K) cumulus clouds
110 Thermosphere 100 90 80 wikimedia.org: Img20050526 0007 at tannheim cumulus.jpg 70 Mesosphere 60 50
40
30 Stratosphere Altitude (km)
20 equatorial
10 polar Troposphere Cu 0 100 150 200 250 300 350 Temperature (K) 110 Thermosphere 100 wikimedia.org: Cumulonimbus_over_The_Netherlands.jpg 90 80 70 Mesosphere 60 50 cumulonimbus clouds 40
30 Stratosphere Altitude (km)
20 equatorial Cb
10 polar Troposphere
0 100 150 200 250 300 350 Temperature (K)
wikimedia.org: Big_Cumulonimbus.JPG cirrus clouds
110 Thermosphere 100 90 80 70 Mesosphere 60 50 Thomas Koop, Bielefeld University
40
30 Stratosphere Altitude (km)
20 equatorial
10 Ci polar Troposphere
0 100 150 200 250 300 350 Temperature (K) Ken Klassy, National Science Foundation
110 Thermosphere 100 90 wikimedia.org: Nacreous_clouds_Antarctica.jpg 80 70 Mesosphere 60 polar stratospheric clouds 50
40
30 Stratosphere Altitude (km)
20 PSC equatorial
10 polar Troposphere
0 100 150 200 250 300 350 Temperature (K) wikimedia.org: Polar_stratospheric_cloud_type_2.jpg wikimedia.org: Noctilucent_clouds_from_ISS_-_13-06-2012.jpg
110 Thermosphere 100 90 80 PMC 70 Mesosphere 60 50
40 wikimedia.org: Noctilucent_clouds_over_saimaa.jpg
30 Stratosphere
Altitude (km) polar mesospheric clouds
20 equatorial
10 polar Troposphere
0 100 150 200 250 300 350 Temperature (K)
wikimedia.org:Helkivad_ööpilved_Kuresoo_kohal.jpg condensed Tg Thom Tm phases: stable ice Ih liquid
metastable LDA ice Ic supercooled liquid
110 Thermosphere 100 90 80 PMC 70 Mesosphere 60 50
40
Stratosphere ozone 30 layer Altitude (km)
20 PSC equatorial Cb
10 Ci polar Troposphere Cu 'weather' fog 0 100 150 200 250 300 350 Temperature (K) Formation of radiation fog % relative humdity 14 n o 90 80 70 ati 60 ur t a supersaturated s r 12 e 50
wat d
liqui 10 wikimedia.org: fog.jpg isobaric cooling 40 (hPa) w
P 8 30
6 subsaturated
20 4 270 275 280 285 290 295 Temperature (K) Formation of radiation fog % relative humdity 14 n o 90 80 70 ati 60 ur t a supersaturated s r 12 e 50
wat d
liqui 10 dew point wikimedia.org: fog.jpg isobaric cooling 40 (hPa) w
P 8 30
6 subsaturated
20 4 270 275 280 285 290 295 Temperature (K) Formation of cumulus clouds % relative humdity 14 n o 90 80 70 ati 60 ur t a supersaturated s r 12 e 50
wat d
liqui adiabatic expansion 10 0m 40 wikimedia.org: 50m Img20050526 0007 at tannheim cumulus.jpg m 2 500 0m 75 (hPa) 00m in rising air parcles w 1250m 10 P 8 on x n i dry e pa s 30 adiabatic 6 subsaturated expansion 20 => air cools by ~10 K per km e.g. 4 270 275 280 285 290 295 @ surface (z=0 km) @ z=1 km: Temperature (K) p = 1000 hPa p = 870 hPa T = 290 K T = 280 K Pw = 9.6 hPa Pw = 8.3 hPa H2 O mixing ratio stays constant but not H2 O partial pressure Formation of cumulus clouds % relative humdity 14 n o 90 80 70 ati 60 ur t a supersaturated s r 12 e 50
wat d
liqui adiabatic expansion 10 0m 40 wikimedia.org: 50m Img20050526 0007 at tannheim cumulus.jpg m 2 500 0m 75 (hPa) 00m in rising air parcles w 1250m 10 P 8 on x n i dry e pa s cloud base 30 adiabatic 6 subsaturated expansion 20 => air cools by ~10 K per km e.g. 4 270 275 280 285 290 295 @ surface (z=0 km) @ z=1 km: Temperature (K) p = 1000 hPa p = 870 hPa T = 290 K T = 280 K Pw = 9.6 hPa Pw = 8.3 hPa H2 O mixing ratio stays constant but not H2 O partial pressure Fog Cumulus clouds
wikimedia.org: wikimedia.org: fog.jpg Img20050526 0007 at tannheim cumulus.jpg 14 14 n ion t 90 80 70 90 80 70 a ati r 60 60 u at atur s o supersaturated supersaturated r 12 eliqu 50 12 e 50 at r s
id w d wa u t li q i 10 dew point 10 isobaric cooling 40 40 (hPa) (hPa) w w
P 8 P 8 sion xpan dry e cloud base 30 30
6 subsaturated 6 subsaturated
20 20 4 4 270 275 280 285 290 295 270 275 280 285 290 295 Temperature (K) Temperature (K) How do droplets condense from water vapor? Homogeneous gas-liq nucleation 5
stable 4 clusters nucleation w and growth 3
w 2 S = P (drop) / P (bulk) 1 bulk limit
for r 8 from Lamb 2011 0 0.0001 0.001 0.01 0.1 1 water cluster/droplet radius (µm) Homogeneous gas-liq nucleation 5
stable 4 Scrit at ~290 K clusters -3 -1 nucleation (for J = 1 cm s ) w and Viisanen et al., J.Chem.Phys. 1993 growth 3 Wölk and Strey, J.Phys.Chem.B 2001
w 2 S = P (drop) / P (bulk) 1 bulk limit
for r 8 from Lamb 2011 0 0.0001 0.001 0.01 0.1 1 water cluster/droplet radius (µm) Not observed in atmosphere! typical values are S < 1.01
Why? => Omnipresent aerosol particles! e.g. H2 SO 4 aerosol particles form Pw in these droplets is by atmospheric oxidation of SO2 smaller than in pure water due to Raoult effect gas-to-particle conversion
SO2 oxidation
H2 SO 4 H2 SO 4 H2 SO 4 H2 SO 4 1.0 nucleation 0.8 w HO2 HO2 HO2 HO2 0.6
adapted with changes from Kathmann et al., Adv.Quant.Chem. 2008 0.4 water activity a
H2 SO 4 is hygroscopic and forms 0.2 aqueous H2 SO 4 droplets 0.0 0.0 0.2 0.4 0.6 0.8
H2 SO 4 mass fraction Köhler theory
1.10 1.020 surface tension effect surface tension effect (Kelvin term) (Kelvin term) 1.015 1.05 1.010
1.00 1.005 combined effect combined Saturation ratio Saturation ratio effect 1.000 0.95 solute effect solute effect (Raoult term) 0.995 (Raoult term)
0.90 0.990 2 4 6 8 2 4 6 8 0.001 0.01 0.1 1 10 0.01 0.1 1 droplet radius (µm) droplet radius (µm)
for 0.01 µm dry H2 SO 4 droplet Köhler theory
1.020
1.015
1.010
1.005 Saturation ratio 1.000
0.995
ambient 0.990 saturation 2 4 6 8 2 4 6 8 rises 0.01 0.1 1 droplet radius (µm) Köhler theory
1.020
1.015
1.010
1.005 Saturation ratio ambient 1.000 saturation rises 0.995
0.990 2 4 6 8 2 4 6 8 0.01 0.1 1 droplet radius (µm) Köhler theory
1.020
1.015 ambient saturation reaches 1.010 activation value 1.005 Saturation ratio 1.000
0.995
0.990 2 4 6 8 2 4 6 8 0.01 0.1 1 droplet radius (µm) Köhler theory
1.020 rcrit
at tiv io S c n 1.015 crit a ambient saturation exceeds 1.010 activation value 1.005 Saturation ratio 1.000
0.995
0.990 2 4 6 8 2 4 6 8 0.01 0.1 1 droplet radius (µm) Köhler theory
1.020 rcrit
at tiv io S c n 1.015 crit a ambient saturation decreases 1.010 "activated" cloud droplet grows 1.005 Saturation ratio 1.000
0.995
0.990 2 4 6 8 2 4 6 8 0.01 0.1 1 droplet radius (µm) Köhler theory Haze Cloud 1.020 rcrit
at tiv io S c n 1.015 crit a
1.010
1.005 stable unstable equilibrium growth Saturation ratio 1.000
0.995
0.990 2 4 6 8 2 4 6 8 0.01 0.1 1 droplet radius (µm) Köhler theory Effect of particle size and chemical composition
1.020
1.015 (1) larger particles 10 nm (1) activate at lower 1.010 dry (1) saturation ratio! radius 25 nm 1.005 (2) solutes with 50 nm (2) larger Raoult effect
Saturation ratio 100 nm 1.000 (2) activate at lower (2) saturation ratio! 0.995 org
H SO 0.990 2 4 2 4 6 2 4 6 2 4 6 0.01 0.1 1 10 droplet radius (µm) Köhler theory Effect of particle size and chemical composition
1.020
1.015 10 nm 1.010 dry radius 25 nm 1.005 50 nm
Saturation ratio 100 nm 1.000 larger particles activate first
0.995 org ambient H SO 0.990 2 4 saturation 2 4 6 2 4 6 2 4 6 rises 0.01 0.1 1 10 droplet radius (µm) Köhler theory Effect of particle size and chemical composition
1.020
1.015 10 nm 1.010 dry radius 25 nm 1.005 50 nm => deplete ambient humidity
Saturation ratio 100 nm 1.000 larger particles activate first
0.995 org ambient H SO 0.990 2 4 saturation 2 4 6 2 4 6 2 4 6 rises more slowly 0.01 0.1 1 10 droplet radius (µm) Köhler theory Effect of particle size and chemical composition
1.020
1.015 10 nm 1.010 dry radius 25 nm 1.005 results in Smax (ambient) 50 nm => deplete ambient humidity
Saturation ratio 100 nm 1.000 larger particles activate first
0.995 org ambient H SO 0.990 2 4 saturation 2 4 6 2 4 6 2 4 6 reaches maximum 0.01 0.1 1 10 droplet radius (µm) Köhler theory Effect of particle size and chemical composition
1.020
1.015 10 nm 1.010 dry X radius no activation X 25 nm 1.005 results in Smax (ambient) 50 nm => deplete ambient humidity
Saturation ratio 100 nm 1.000 larger particles activate first
0.995 org activation ambient H SO 0.990 2 4 saturation 2 4 6 2 4 6 2 4 6 decreases 0.01 0.1 1 10 droplet radius (µm) Cloud Condensation Nuclei = CCN
1000
800 dry ) particles -3
600
400
dN/dlog(r) (cm 200
0 0.001 0.01 0.1 1 10 100 radius (µm)
after Baltensperger, Science 2010 Cloud Condensation Nuclei = CCN
1000 critical radius for activation 800 dry ) particles -3
600
400
dN/dlog(r) (cm 200 CCN 0 0.001 0.01 0.1 1 10 100 radius (µm)
after Baltensperger, Science 2010 Cloud Condensation Nuclei = CCN
1000 critical radius for activation 800 dry ) particles cloud -3 droplets 600
activation 400
dN/dlog(r) (cm 200
0 0.001 0.01 0.1 1 10 100 radius (µm)
after Baltensperger, Science 2010 Variability in aerosol composition...
from Andreae and Rosenfeld, Earth-Science Rev. 2008
...results in differences in activation diameter
from Andreae and Rosenfeld, Earth-Science Rev. 2008 suggests potential human influence on number of cloud droplets
from Andreae and Rosenfeld, Earth-Science Rev. 2008 Ship tracks
thick stratocumulus clouds thin thin stratocumulus ship stratocumulus clouds track clouds
thin
stratocumulus e clouds r [µm]
high reflectivity clouds: "ship tracks" e r [µm]
Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC -3 # cloud drops [cm ]
NASA distance across track [km] adapted from Seinfeld and Pandis 1998 Albedo effect (Twomey effect, J.Atmos.Sci. 1977)
Clean Larger drops More rain
Less cloud-active aerosol
t = 10 min t = 20 min Polluted Smaller drops Less rain
More cloud-active aerosol adapted from B Stevens & G Feingold Nature 461, 607-613 (2009) doi:10.1038/nature08281 => brighter clouds Satellite observations of clouds Effect of urban and industrial air pollution on clouds: brighter clouds suppresion of rain
lead smelter
power plant re ~ 5-10 µm wind direct ion cement plant and port
oil refineries re ~15-25 µm
South Australia 12. Aug 1997
Blue: Clear skyK
Red: Low reflectivity cloudsK Yellow: High reflectivity clouds
adapted from Rosenfeld, Science 2000 Albedo effect Lifetime effect (Twomey effect, J.Atmos.Sci. 1977) (Albrecht effect, Science 1989)
Clean Larger drops More rain
Less cloud
Less cloud-active aerosol
t = 10 min t = 20 min t = 30 min t = 40 min t = 50 min t = 60 min Polluted Smaller drops Less rain
More cloud
More cloud-active aerosol adapted from B Stevens & G Feingold Nature 461, 607-613 (2009) doi:10.1038/nature08281 => brighter clouds => less precipitation more long-lived clouds What about clouds below O °C? e.g. cumulonimbus clouds
wikimedia.org: Big_Cumulonimbus.JPG
very cold when does } freezing occur? cold condensation
warm clear air D.G. Fahrenheit, Philos. Trans. Roy. Soc. London, 1724 Thermodynamic Kinetic
Liquid stable
Tm
Liquid metastable
Crystal stable Nucleus
Temperature Heterogeneous Nucleation
Homogeneous Nucleation one bulk sample
ice nucleus
whole sample freezes heterogeneously
many small samples
one sample freezes heterogeneously
all other samples freeze homogeneously Emulsion calorimetry
220 230 240 250 260 270 280
Thom Cooling
water-in-oil emulsion
Emulsion droplets from Heat flow (a.u.) Warming microfluidic device Tm
220 230 240 250 260 270 280 Temperatur (K) 500µm
Riechers, Wittbracht, Hütten, Koop, PCCP 2013 Homogeneous ice nucleation rate coefficient in pure water
11 10
10 10 temperature uncertainty ±0.5 K 9 10 µm droplet 10 frezes in ~ 1s
8
) 10 -1 s
-3 7 smaller droplets or 10 higher cooling rate
(T) (cm 6
V 10 J Pruppacher (1995) => lower freezing Murray (2010) 5 Kuhn (2011) temperature 10 Stöckel (2005) Wood (2002) Krämer (1999) Ladino (2011) Duft (2004) 4 Lüönd (2010) 10 Rzesanke (2012) Hoyle (2011) Benz (2005) Knopf (2011) DeMott (1990) 3 Stan (2009) this work 10 235 236 237 238 T (K)
adapted from Riechers et al. PCCP 2013 In situ data of deep convective clouds in Texas
-40
-30
-20
-10
Temperature [°C] Temperature 0
10
Supercooled liquid Median volume water content [g/m³] droplet diameter [µm]
Rosenfeld and Woodley, Nature 2000 In situ data of deep convective clouds in Texas
Homogeneous -37.5 °C ice nucleation Temperature [°C] Temperature
Supercooled liquid Median volume water content [g/m³] droplet diameter [µm]
Rosenfeld and Woodley, Nature 2000 So only homogeneous ice nucleation in atmospheric water droplets? => NO
Atmospheric observations of ice in clouds
heterogeneous ice nucleation
all ice homogeneous ice nucleation all supercooled liquid
Murray et al., Chem.Soc.Rev. 2012
particles triggering heterogeneous ice nucleation are termed Ice Nuclei = IN Types of IN example from a cloud at 8 km altitude (only 46 particles!)
Salt (NaCl/KCl) Organic carbon-nitrate
Mineral Soot dust
Biological
from Pratt et al., Nat.Geosci. 2009 Heterogeneus ice nucleation induced by biological particles
Bacteria: Pseudomonas Syringae
Droplets with ice nuclei freeze heterogeneously
Droplets without ice nuclei from Morris et al., J.Phys.IV France 2004 freeze homogeneously commercial product: Snomax®
wikimedia.org:Schneekanone.jpg Heterogeneus ice nucleation induced by biological particles
Bacteria: Pseudomonas Syringae Koop and Zobrist, PCCP 2009
Thom Thet
from Morris et al., J.Phys.IV France 2004 commercial product: Snomax® Heat Flow [a.u.]
190 210 230 250 270 Temperature [K]
wikimedia.org:Schneekanone.jpg BINARY: B ielefeld I ce N ucleation AR ra Y
a) setup b) sample cell side view top glass slide polymer spacer bottom glass slide individual compartments with single water droplets
PC CCD camera c) sample cell top view
polymer spacer objective control individual compartment unit single water droplet
window dry N2 purge gas sample cell heat 1 cm Peltier cooling stage sink bath housing Snomax in water
V = 1 µL Snomax in water
0 V = 1 µL -5
-10
-15 [°C] f
T -20
-25
-30
-35 -8 -7 -6 -5 -4 -3 -2 -1 0 10 10 10 10 10 10 10 10 10 c [µg/droplet] Frozen Fraction Active Sites per mg of Snomax perform lab perform field calculate atmospheric measurements measurements IN concentrations
active site density IN concentration 8 atmospheric abundance 10 very active -4 7 10 10 important -6 6 10 10 size concentration of air -8
5 -3 10 10 -3 of surface area 1 µm 100 cm (abundant) -10 -2 4 10 10 2 µm 1 m-3 (very rare) -12 3 10 moderately 10 active 2 -14 less important 10 10 (only at high T)
1 active IN per cm -16 10 10 0 -18 active sites per cm 10 10 -40 -30 -20 -10 0 -40 -30 -20 -10 0 Temperature (°C) Temperature (°C) More realistic values:
101
10-1 -3 mineral -3 dust 10 soot EC
10-5
-7 10 Complexity of the problem:
10-9 homogeneous ¤ high variability/uncertainty in activity fungal bacteria K IN concentration (cm ) spores 10-11 ¤ modification during atmospherice lifetimeK ¤ uncertainty in concentrationsK 10-13 -40 -30 -20 -10 0 ¤ high temporal and spatial variability Temperature (°C) adapted with changes from Cziczo et al., Science 2013
Only very low concentrations of IN! Why do we care? 1922: forest on a hill (~450 m) near Oslo
stratus layer
supercooled stratus layer
Tor Bergeron, 1972 HO2
HO2
supercooled water droplets ice particles
For temperatures below 273.16 K: pliq > pice supercooled water droplets ice particles
For temperatures below 273.16 K: pliq > pice Vapor pressures of ice and supercooled water
pliq 1 pice
10-1 p -2 p10 [hPa] p or 10-3
Scheel and Heuse (1909) Bottomley (1978) Kraus and Greer (1984) 10-4 Fukuta and Gramada (2003) 180 200 220 240 260 Temperature [K]
Murohy and Koop, Q.J.Roy.Met.Soc. 2005 The Wegener-Bergeron-Findeisen process in mixed-phase clouds
a Liquid cloud droplet Ice nucleus = IN Ice nucleus
cooling/ supercooling b
Heterogeneous ice nucleation
adapted with changes from Koop and Nahowald, Nature 2013 The Wegener-Bergeron-Findeisen process in mixed-phase clouds
a Liquid cloud droplet Ice nucleus = IN Ice nucleus
b
Ice crystal Water vapor transfer Supercooled droplets
c Questions:K Atmospheric concentration of IN?K What are they made of?K Activation temperatures?
Sedimentation adapted with changes from Koop and Nahowald, Nature 2013 water What about clouds that droplet develop below -40 °C? ice cloud particle freezing droplet 100 %
CCN activation
dilute aerosol liquid freezing aerosol droplets
HO2 HO2 concentrated Relative Humidity HO2 HO2 HO2 HO2
Thom = -40°C 0 %
Temperature cirrus polar clouds stratospheric clouds
Thomas Koop, Bielefeld University wikimedia.org: Polar_stratospheric_cloud_type_2.jpg Homogeneous Ice Nucleation: the Effect of Solutes
H2SO4 (a) 260 Tm 240
220
200 Temperature [K]
180 Tf
0 10 20 30 Molality [mol kg-1]
Koop et al., Nature 2000 Homogeneous Ice Nucleation: the Effect of Solutes
H2SO4 (a) HNO3 260 (NH4)HSO4 Tm (NH4)2SO4 NH4NO3 240 Sea salt LiCl 220 NaCl KCl 4 200
NH F Temperature [K] NH4Cl CaCl2 180 Tf MgCl2 MnCl2 0 10 20 30 Ca(NO3)2 -1 H2O2 Molality [mol kg ] Urea Ethylen glycol Glycerol Glucose Poly(ethylen glycol)
Koop et al., Nature 2000 Homogeneous Ice Nucleation: the Effect of Solutes
H2SO4 (a) (b) HNO3 260 (NH4)HSO4 stable Tm liquid (NH4)2SO4 NH4NO3 240 Sea salt metastable LiCl 220 liquid NaCl KCl T 4 200 m
NH F Temperature [K] NH4Cl CaCl2 T ``no man's 180 f Tf MgCl2 land'' MnCl2 0 10 20 30 .. 0.50.60.70.80.91.0 Ca(NO3)2 -1 H2O2 Molality [mol kg ] Water activity aw Urea Ethylen glycol Glycerol aw = Relative Humidity Glucose Poly(ethylen glycol)
Koop et al., Nature 2000 Comparison Model Prediction vs. Field Measurements
200 Relative Humidity w at er s w.r.t. Ice: atu rat model p ion rediction PSC 150 (22 km) Cirrus (12 km) Cirrus (8 km)
ice saturation [%] 100 RHI
50
0 180 190 200 210 220 230 240 250 Temperature [K] RHI (%) 100 160 220 Altitude (km) nucleation threshold Homogeneous icenucleationinaerosolparticles ice particlesnucleate Time (minutestohours) gas phasewatertosaturation ice particlesgrowanddeplete Peter, Marcolli,Spichtinger, Corti,Baker, Koop,Science 2006 Koop and Zobrist, PCCP 2009 Competition: solute decreasenucleation IN increasenucleation Emulsion withsuspendedSnomaxparticles
9 1 3 5 270 250 230 210 190 Heat Flow [a.u.] e prtr [K] Temperature T hom T het Concentration: Glucose wt% 0 0wt% 20 wt% 30 Heterogeneous ice nucleation in aqueous solutions
290 H2SO4 Glucose 270 PEG400 (NH4)2SO4 (NH4)2SO4 PEG6000 250 T m
Thet 230 (Snomax) Thet (ATD) Temperature [K] Temperature aw,het (ATD) 210 aw,het (Snomax) Thom aw,hom 190 1.0 0.9 0.8 0.7 0.6 0.5 water activity
IN
Koop and Zobrist, PCCP 2009 Other types of heterogeneous ice nucleation
from Lamb and Verlinde, Physics and Chemistry of Clouds, 2011 => highly recommended! polar mesospheric clouds 10-50 nm ice particles a few hundred up to max 1000 cm-3
formation mechanism? heterogeneous ice nucleation on meteoritic smoke particlesK
wikimedia.org: Noctilucent_clouds_from_ISS_-_13-06-2012.jpg
Lübken et al., J.Atmos.Sol.Terr.Phys. 2009
in the absence of PMSE in the presence of PMSE
Lübken et al., J.Atmos.Sol.Terr.Phys. 2009 polar mesospheric clouds 10-50 nm ice particles a few hundred up to max 1000 cm-3
formation mechanism? heterogeneous ice nucleation on meteoritic smoke particlesK homogeneous nucleation of LDA wikimedia.org: Noctilucent_clouds_from_ISS_-_13-06-2012.jpg then crystallization to ice Ic critical saturation ratio for homogeneous nucleation
Lübken et al., J.Atmos.Sol.Terr.Phys. 2009
Murray and Jensen, J.Atmos.Sol.Terr.Phys. 2010 Metastability of atmospheric water
X = ice Ih X = liquid 9 water 10
7 10
5 10
3 g-cr 10 ng -a n c uc lea al e tio ti nu 1 on 10 g-l nucl ae onti 2.5
2.0
nl -cr uc tl ea i no Water saturation ratio w.r.t. X saturation ratio w.r.t. Water 1.5
supersaturated ice Ih liquid 1.0 subsaturated
100 150 200 250 300 350 Temperature (K) Is it possible to observe water's metastability in the sky with the naked eye? (1) supercooled liquid water: hole-punch and canal clouds (rare!)
Jeff Schmaltz, MODIS Rapid Response Team, NASA Goddard Space Flight Center. wikimedia.org: Texas_tmo_2007029_lrg.jpg
from Heymfield et al., Science 2011 (2) ice-supersaturatedclearair: Is itpossibletoobservewater'smetastabilityintheskywithnakedeye? temporary contrail wikimedia.org: Contrail_Marki_2.JPG ice particles => airissub- saturated evaporate form ice particles
wikimedia.org: Contrail_Marki_2.JPG contrails(notsorare!)
wikimedia.org: Contrails.jpg sometimes transforminginto cirrus ice particlessurviveforlong times permanent contrails => airissuper-saturated Is it possible to observe water's metastability in the sky with the naked eye? (3) ice-supersaturated mesospheric air: space shuttle contrails (VERY rare!)
NASA Photo/Houston Chronicle, Smiley N. Pool
Launch of Space Shuttle Atlantis on July 8, 2011 Stevens et al., JGR 2012 Shuttle-induced polar mesospheric cloud over Wismar, Germany on July 9, 2011 tracked by satellite brighter than 99% of PMCs
Leibniz-Institute of Atmospheric Physics Is it possible to observe water's metastability in the sky with the naked eye?
X = ice Ih X = liquid 9 water 9 10 10
7 shuttle-induced 7 10 10 polar mesospheric clouds 5 5 10 10
3 3 g nu- io 10 nug -a cr c 10 leat cl ae ti n 1 on 1 10 g-l n cu le tia no 10 2.5 permanent 2.0 contrails
l c- r n u lec ation Water saturation ratio w.r.t. X saturation ratio w.r.t. Water 1.5 hole-punch and canal clouds
supersaturated ice Ih liquid 1.0 subsaturated
100 150 200 250 300 350 Temperature (K)