" (...) The Soviet Union created a specifically designed version of the Antonov An-30 aerial survey aircraft, the An-30M Sky Cleaner, with eight containers of solid carbon dioxide in the cargo area plus external pods containing meteorological cartridges that could be fired into clouds.[49] Soviet military pilots seeded clouds over the Belorussian SSR after the Chernobyl disaster to remove radioactive particles from clouds heading toward Moscow.[50] At the July 2006 G8 Summit, President Putin commented that air force jets had been deployed to seed incoming clouds so they rained over Finland. Rain drenched the summit anyway.[51] In Moscow, the Russian Airforce tried seeding clouds with bags of cement on June 17, 2008. One of the bags did not pulverize and went through the roof of a house.[52] In October 2009, the Mayor of Moscow promised a 'winter without snow' for the city after revealing efforts by the Russian Air Force to seed the clouds upwind from Moscow throughout the winter.[53] (...)"
http://en.wikipedia.org/wiki/Cloud_seeding#cite_note-50