por Precipitation, which washes both aerosol particles and vapor out of the atmosphere Factors increasing the danger of the primary cloud tend to be the opposites of those previously cited:Steady wind direction Wind velocity under 3 m s-1 Stable air (inversion) Temperature above 20C No precipitation http://www.mitretek.org/mission/envene/chemical/history/ww1.htmlChlorine GasAt 5 PM on 22 April 1915, German troops at Ypres discharged 180,000 kg of chlorine gas from 5,730 cylinders on the line between Steenstraat on the Yser Canal, through Bixschoote and Langemark, to Poelcappelle. The gas cloud blew with the wind, and either killed or caused the French and Algerian troops in the opposing trenches to flee, opening an 8 to 9 km gap in the Allied line. On 24 April 1915, the Germans conducted a second chlorine gas attack at Ypres, this time against Canadian troops.On 31 May 1915, chlorine was first employed on the eastern front, by the Germans at Bolimow, near Skierniewice, 50 km southeast of Warsaw. This attack employed 12,000 cylinders, releasing 264 tons of chlorine along a 12 km line. There were nearly 200 chemical attacks during World War I using gas released from cylinders; the largest of these occurred in October 1915 when the Germans released 550 tons of chlorine from 25,000 cylinders at Rhiems.Prof. Fritz Haber *http://www.nobel.se/chemistry/laureates/1918/haber-bio.html* was chief of the German chemical warfare service during World War I and personally directed the first chlorine gas attack. Haber, a Nobel laureate and known for his discovery of a process for synthesizing ammonia by the combination of nitrogen and hydrogen, is often referred to as the father of chemical warfare.Back to Top *ww1.html* The Antecedents of Chemical WarfareMany chronicles of the history of chemical warfare *history.html*begin with "At 5 PM on 22 April 1915...." What is perhaps less appreciated is that the first chlorine attack represented merely an es...
