Condensation nuclei
Lecture 19
Absolutely pure air
Condensation is possible only on molecules 
300-400 % supersaturation is needed (see Lec.18) results obtained in Wilson cloud chamber are the same
Cloud Chamber of
Carl Anderson (ca. 1935)
http://www.orau.org/ptp/collection/miscellaneous/cloudchamber.htm
Starting condensation on molecules requeres 1200% supersaturation.
Lecture 19. Condensation |
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nuclei |
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2 types of condensation nuclei in the real atmosphere
Insoluble but moistured
Soil
Rocks
Smoke
Organic substances
etc
Soluble
Particles of salts and acids (due to coal burning)
Coal contains 0.3-20% sulfur burning SO2
SO2 H2SO4 (soluble, hygroscopical)
20 million tonns of SO2 arrive
the atm. annualy |
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As a result of earth surface airing, forest fires, volcano eruptions |
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Lecture 19. Condensation |
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nuclei |
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http://homepages.nyu.edu/~pet205/sulfur3.gif
Lecture 19. Condensation |
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nuclei |
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The above satellite image clearly demonstrates the effect of cloud condensation nuclei on cloud formation. Ships travelling the ocean off of Europe produce aerosols as they burn fuel, and those aerosols help to form low clouds in the shallow, cool, and moist layer of marine air that exists there.
Lecture 19. Condensation |
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http://www.weatherquestions.com/What_are_condensation_nuclei.htm
nuclei
plume_910612.jpg
.svg
Lecture 19. Condensation |
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nuclei |
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Water-absorbing nuclei from marine splashes, froth
NaCl 77.8%
MgCl 10.9%
Sulfur oxides of Mg (magnesium), K (potassium), Ca
Strong wind (>10 m/s) 2.7*10 10 tons of marine salt come
into atm. annually
Lecture nuclei
Nuclei distribution according to…
1. Concentration (number
per cm3 near earth surface)
At large cities – 150000
At small towns -35000
At villages -9500
Over oceans, in mountains -940
SPb -280000(RSHU measurements)
2. Their nature:
Marine origin nuclei -20%
Burning products – 40%
Soil particles -20%
Unknown origin – 20%
Lecture 19. Condensation |
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nuclei |
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Nuclei
Active |
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Passive |
taking |
part |
in over land; |
condensation |
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process; |
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in the |
lower |
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part |
of |
a |
cloud |
their |
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number is 102 to 103 per cm3
;
over sea;
Balloon measurements
Z, km |
n |
0 |
13000 |
0.1-0.5 |
8800 |
0.5-1.0 |
3250 |
1.0-1.5 |
2540 |
1.5-2.0 |
1440 |
2.0-2.5 |
1170 |
2.5-3.0 |
640 |
3.0-4.0 |
340 |
Lecture 19. Condensation |
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nuclei |
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Nuclei concentration variation with height depends on thermal stratification
Day time: unstable stratification, intensive eddy exchange rate of variation is slow
Early morning: stable stratification, weak eddy exchange rate of variation is faster
n(z) n0e z / l
l is not const, ~ location
ll
"0"ground level
L=1400 m for Moscow, layer 0-3 km
L=1740 m for Moscow, layer 3-6 km
Lecture 19. Condensation |
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nuclei |
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