🗊Презентация Condensation nuclei

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.

2 types of condensation nuclei in the real atmosphere Insoluble but moistured Soil Rocks Smoke Organic substances etc

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.

Ash plume of Pinatubo during 12, June 1991

Water-absorbing nuclei  from marine splashes, froth 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

Nuclei distribution according to… 2. Their nature: Marine origin nuclei -20% Burning products – 40% Soil particles -20% Unknown origin – 20%

Nuclei Active taking part in condensation process; in the lower part of a cloud their number is 102 to 103 per cm3 ; over sea;

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

In summer eddy exchange is well developed and nuclei are transferred to the upper atmospheric layers In winter : dwellings heating

Size variation 5*10-7 <r< 2*10-6 cm Aitken nuclei 2*10-6 <r< 10-4 cm large nuclei r> 10-4 cm giant nuclei (human hair diameter ~ 10-3 cm )

Aerosol pollution over Northern India and Bangladesh 2001-12-04 The skies over Northern India are filled with a thick soup of aerosol particles all along the southern edge of the Himalayan Mountains, and streaming southward over Bangladesh and the Bay of Bengal. Notice that the air over the Tibetan Plateau to the north of the Himalayas is very clear, whereas the view of the land surface south of the mountains is obstructed by the brownish haze. Most of this air pollution comes from human activities. The aerosol over this region is notoriously rich in sulfates, nitrates, organic and black carbon, and fly ash. These particles not only represent a health hazard to those people living in the region, but scientists have also recently found that they can have a significant impact on the region's hydrological cycle and climate Credit Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC http://visibleearth.nasa.gov/view_rec.php?id=2309