Silver iodide, cloud seeding

Cloud point (CP), 75 207 24 126 Cloud seeding, silver iodide in, 22 685 Clove bud oil, 24 542 Clove buds, 23 166 Clove leaf oil, in perfumes, 78 367 Cloverite, 76 820 Cloves, 23 155 Cloxacillin, 3 33 Cloxyfonac, 73 4 It, 48 C1S03H, fatty alcohol sulfation with, 23 541. See also Chlorosulfonic acid Clupanodonic acid, physical properties, 5 33t... 

From seeding clouds with silver iodide Usually 10-300 Max. 4500 1,2... 

Figure 2.2 (a) Absorption and emission processes between states m and n. (b) Seeding of a rain cloud with silver iodide (Agl) to induce a shower of rain... 

Cloud Seeding. In 1947, it was demonstrated that silver iodide could initiate ice crystal formation because, in the [ -crystalline form, it is isomorphic with ice crystals. As a result, cloud seeding with silver iodide has been used in weather modifications attempts such as increases and decreases in precipitation (rain or snow) and the dissipation of fog. Optimum conditions for cloud seeding are present when precipitation is possible but the nuclei for the crystalliza tion of water are lacking. 

Fig. 9.2. The excellent crystallographic matching between silver iodide and ice makes silver iodide a very potent nucleating agent for ice crystals. When clouds at sub-zero temperatures are seeded with Agl dust, spectacular rainfall occurs.

Pollution can cause opposite effects in relahon to precipitation. Addition of a few particles that act as ice nuclei can cause ice particles to grow at the expense of supercooled water droplets, producing particles large enough to fall as precipitation. An example of this is commercial cloud seeding with silver iodide particles released from aircraft to induce rain. If too many particles are added, none of them grow sufficiently to cause precipitation. Therefore, the effects of pollution on precipitation are complex. 

On a smaller scale, the largest producer of iodine is Japan where it is extracted from. seaweed containing more than 0.05 parts per million. The most important industrial iodine compound is silver iodide used with silver bromide in photography. Iodine is important in medicine for treating thyroid problems by adding it to table salt. It is used directly as a disinfectant, and a component of d vs. Crystalline silver iodide is used for cloud seeding. 

A To divert storms, clouds can be seeded with silver iodide crystals to promote "targeted" rain. 

Alpine lake, Colorado, 1973-74. Silver iodide (43 kg), equivalent to 19.7 kg silver, released into system from local cloud seeding practices between 1963 and 1973 Lake water, 1973 vs. 1974... 

Silver iodide, 14 370, 22 671 in cloud seeding, 22 685 natural occurrence of, 22 668 Silver ion activity, in photographic crystal growth, 19 179 Silver-ion reduction... 

Crystals of silver iodide (Agl), in addition to being useful in photographic processing, are used to seed clouds. The atmospheric conditions (humidity and such) must be right for this to work because the tiny crystals act as nuclei on which moisture can condense with the expectation that the small droplets will become heavy enough to drop to earth—as rain. 

Iodine is also used as a test for starch. When placed on starch (a potato for example), iodine turns the starch a dark blue color. Silver iodide is used in the manufacture of photographic film and paper. It is also used to seed clouds because of its ability to form a large number of crystals that act as nuclei upon which moisture in the clouds condenses, forming raindrops that may result in rain. 

Silver iodide is used in cloud seeding for artificial rain making and in photography. Its colloidal suspension is used as a local antiseptic. 

Minor industrial uses include the application of silver iodide as a smoke for the seeding of clouds to induce rainfall. Compounds used for obtaining some nonflammable plastics and cellulose are benzyltriphenyl-phosphoniumiodides and [2,-(acetyloxy)ethyl] triphenyl-phosphoniumiodides (see Flame RETARDANTS, HALOGENATED FLAME retardants) (142). The addition of iodine to an aromatic hydrocarbon such as -butylbenzene results in the formation of charge-transfer complexes that display outstanding effectiveness as lubricants for hard-to-lubricate metals (143), such as titanium or steels (see also LUBRICATION AND LUBRICANTS). Iodine is also used in the production of high purity metals such as titanium, silicon, hafnium, and zirconium (144). 

The total U.S. annual anthropogenic release of silver to the atmosphere from production processes and consumptive uses in 1978 was estimated at 77,700 kg (Scow et al. 1981). Of this amount, an estimated 30,000 kg were released from metals production, 22.000 kg from use in electrical contacts and conductors, 9,000 kg from coal and petroleum combustion, 7,000 kg from iron and steel production, 2,000 kg from cement manufacture, and the remainder from miscellaneous uses. Urban refuse was the source of an additional 10,000 kg. Smith and Carson (1977) estimated that cloud seeding with silver iodide contributed 3,100 kg annually (based on data from the early 1970s). 

Silver was measured in particulate samples from rural and urban areas both adjacent to and removed from activities such as metal smelting, refining, and silver iodide cloud seeding. 

Silver iodide powder has been used as an antiseptic and as an agent to seed clouds for rain. Silver iodide is 45.9% silver by mass. If you separate a 50-g sample of silver iodide into its elements, silver and iodine, how much silver would you have ... 

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