Watch this amazing smoke screen that was practiced during World War II. It was administered from aircraft to generate vertical smoke curtains and was composed of Titanium tetrachloride (FM).
Titanium tetrachloride (FM) is a colorless, non-flammable, corrosive liquid. In contact with damp air, it hydrolyzes quickly, ending in a dense white smoke consisting of droplets of hydrochloric acid and bits of titanium oxychloride. [source]