Rain making

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

Some Famous Lead Mines. J.-P. de Toumefort, who visited the Levant in 1700, wrote Siphanto, in days of yore, was famed for its rich Gold and Silver Mines . . . Besides the Mines aforesaid, they have plenty of Lead the Rains make a plain discovery of this, go almost where you will throughout the whole Island. The Oar is greyish, sleek, and yields a Lead like Pewter (210). 

D. A. Davies [7] suggested the use of explosive charges for rain-making. The charges, consisting of 15 g of blackpowder plus 1.5% of silver iodide, are sent by balloon into a cloud, where they are exploded by a time fuse. The particles of silver iodide thus released act as nuclei on which the water vapour in a raincloud coagulates, to fall as rain drops. 

Much has been written in recent years about atmospheric inputs to the soil since the acid rain problem has been recognised. Soils receive both wet deposition, ie, precipitation as rain or snow and dry deposition in which aerosols are deposited on the surface. Although precipitation is very dilute it can be an important source for some elements, cyclic salts which are derived from the oceans and transported to the land surface in the normal hydrological cycling of elements. Fuge and Johnson (1986) concluded that most iodine in soils is derived from the atmosphere and, hence, the oceans. Normally, however, rain makes only a very small contribution to the composi-... 

The enriched acidity of the rain (mentioned above) means that when it falls on the ground it dissolves essential ions, including magnesium, out of the soil. Magnesium ions are essential for photosynthesis, and so plant growth is affected. Acid rain also dissolves some of the more toxic ions, such as aluminium, copper, lead and zinc, out of the soil. These metals under normal conditions remain fixed in the soil, but acid rain makes these toxic elements more available to plant life. These elements stunt the growth of plants. The water run-off from the soil into rivers and lakes means a build-up of toxic ions, and aquatic plants and fish are affected. 

For small rockets (signal, distress and life-saving at sea rockets), rockets for rain-making (Vol. Ill, p. 324). 

While interest in the United States has focused on the aborting of hurricanes and to a lesser extent on rain-making, it appears that the major Russian interest is in hail prevention. A secondary effect of causing precipitation by cloud-seeding is the removal of clouds and of fog. It has been possible to create enough of a hole in a cloud and fog layer over an airport to enable planes to resume operations (Salt Lake Qty, Utah, December 1962). ... 

It is not impossible, for example in weather modification (rain making, hail prevention and fog dissipation), but almost through catalytic triggering. 

A geoengineering approach based on production of light-reflecting atmospheric sulfate aerosols would entail discharging large quantities of sulfur dioxide from the anthrosphere into the atmosphere. The enormous quantities of sulfur dioxide required and the collateral consequences, particularly increased acid rain, make it unlikely that this solution will ever be employed. 

Sulphur dioxide forms because petrol contains a little sulphur. It attacks the lungs and breathing tubes, causing bronchitis and other diseases. It also dissolves in rain, making it acidic. The acid rain damages trees, plants, buildings, and metalwork. 

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