Expansion/decompression of gas results in lowering its temperature.
The demonstration seen in the following video demonstrates this principle. The expansion of CO2 from its compressed/liquid state in the cylinder lowers the temperature and draws off heat sufficiently to freeze a small portion of the CO2 into dry ice. http://mad-science.wonderhowto.com/how-to/make-dry-ice-home-using-co2-fire-extinguisher-0141908/