Cirri

Clouds cover roughly two-thirds of our earth s surface and play an important role in influencing global climate by affecting the radiation budget. Cirrus clouds are one example of a cloud type whose optical properties are not accurately known. Cirrus clouds form in the upper troposphere and are composed almost exclusively of non-spherical ice crystal particles. The impact of cloud coverage on dispersion of pollution in the atmosphere is an area of great concern and intensive study. 

Solar beating of tropical oceans warms the surface water, promoting evaporation. Where the equatorial surface waters are warmest and the northeast and southeast trade winds meet, a band of cirrostratus and cirrus clouds spreads out from convective precipitation regions. This area is known as the Intertropical Convergence Zone. 

Since feedbacks may have a large potential for control of albedo and therefore temperature, it seems necessary to highlight them as targets for study and research. Besides the simple example above of cloud area or cloud extent, there are others that can be identified. High-altitude ice clouds, for example, (cirrus) have both an albedo effect and a greenhouse effect. Their occurrence is very sensitive to the amount of water vapor in the upper troposphere and to the thermal structure of the atmosphere. There may also be missing feedbacks. 

Radiation in the far IR from either cool dust associated with cirrus or warm dust associated with active star formation in luminous and ultra-luminous infrared galaxies. 

Borrmann, S S. Solomon, L. Aval lone, D. Toohey, and D. Baumgardner, On the Occurrence of CIO in Cirrus Clouds and Volcanic Aerosol in the Tropopause Region, Geophys. Res. Lett., 24, 2011-2014 (1997a). 

Number concentrations of ice crystals in cirrus clouds have also been observed to increase with aerosol particle concentrations (with diameters >0.018 /tm) and, in particular, with the concentration of light-absorbing materials in the ice crystals (Strom and Ohlsson, 1998). 

Fu, R., A. D. Del Genio, W. B. Rossow, and W. T. Liu, Cirrus-Cloud Thermostat for Tropical Sea Surface Temperatures Tested Using Satellite Data, Nature, 358, 394-397 (1992). 

Heymsfield, A. J., Microphysical Structures of Stratiform and Cirrus Clouds, in Aerosol-Cloud-Climate Interactions (P. V. Hobbs, Ed.), pp. 97-121, Academic Press, San Diego, 1993. 

Laaksonen, A., J. Hienola, M. Kulmala, and F. Arnold, Supercooled Cirrus Cloud Formation Modified by Nitric Acid Pollution of the Upper Troposphere, Geophys. Res. Lett., 24, 3009-3012 (1997). 

Ramanathan, V., and W. Collins, Thermodynamic Regulation of Ocean Warming by Cirrus Clouds Deduced from Observations of 1987 El Nino, Nature, 351, 27-32 (1991). 

Ramaswamy, V., and V. Ramanathan, Solar Absorption by Cirrus Clouds and the Maintenance of the Tropical Upper Troposphere Thermal Structure, J. Atmos. Sci., 46, 2293-2310 (1989). 

Strom, J., and S. Ohlsson, In Situ Measurements of Enhanced Crystal Number Densities in Cirrus Clouds Caused by Aircraft Exhaust, J. Geophys. Res., 103, 11355-11361 (1998). 

Clouds that are formed when the dew point is below the freezing point Cirrus... 

Cirrus clouds - high, thin, feathery clouds... 

Many uncertainties also remain about the impact of present changes in extra-atmospheric insolation on climate. Soon et al. (2000) detected, for instance, the super-sensitivity of the climate system to changes in UV insolation whose impact is enhanced by the feedback due to the statistical stability of clouds, influence of tropical cirrus clouds, and stratospheric ozone (the ozone-climate problem needs special analysis) (Kondratyev and Varotsos, 2000). 

In Schistocephalus, worms cultured free in liquid media fail to inseminate and the cirrus can often be observed projecting from the genital pore and the... 

Some cestodes (e.g. the Acoelidae) lack a vaginal opening and insemination apparently occurs by the well-armed cirrus being thrust into the tissues of the body wall from which spermatozoa migrate to the large seminal vesicle (889). The same mechanism occurs in some monogeneans, e.g. Diclidophora. 

Fig. 10.2. Culture tube which enables the pseudophyllidean Schistocephalus solidus to undergo insemination during maturation in vitro at 40°C. Fertile eggs are produced only by worms compressed during maturation, a process which enables the cirrus to enter the vagina in each proglottis. Eggs from worms maturing free in the medium produce only infertile eggs. (After Smyth, 1982.)...

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