Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature - Khosrawi, F.; Urban, J.; Lossow, S.; Stiller, G.; Weigel, K.; Braesicke, P.; Pitts, M. C.; Rozanov, A.; Burrows, J. P.; Murtagh, D. (Atmos. Chem. Phys., 2016)