"Cloud seeding causes precipitation by introducing substances into cumulus clouds that cause condensation. Most seeding uses silver iodide, but dry ice (solid carbon dioxide), propane, and salt are also used. At least 30 countries have identified programs and some, like China and the United States, have extensive programs (See Figure 1). Most countries that practice cloud seeding are parties to the ENMOD treaty, but China is not." United Kingdom House of Commons Science and Technology Committee The Regulation of Geoengineering Fifth Report of Session 2009–10 Report, together with formal minutes, oral and written evidence Ordered by the House of Commons to be printed 10 March 2010 http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/221/221.pdf page Ev 33
