“…Water vapour is the most important atmospheric trace gas and a key compound of the global climate (Ciais et al, 2004;Gedzelman et al, 2003;Hartmann, 2002;Lawrence et al, 2002;Smith, 1992). It plays an important role in many atmospheric processes, such as radiative transfer, circulation dynamics Hanisco et al, 2007;Kuang et al, 2003;Johnson et al, 2001;Moyer et al, 1996), stratospheric chemistry (Steinwagner et al, 2007;Rosenlof et al, 2001Rosenlof et al, , 2003McCarthy et al, 2004;Franz et al, 2005;Coffey et al, 2006), cloud formation (Schmidt et al, 2005), precipitation (Bowen and Revenaugh, 2003) and the greenhouse effect (Schneider et al, 1999;Hartmann, 2002).…”