1. [8 Pts] Air-vapor(water) mixtures. (a) Shortly explain why the specific humidity in summer is usually higher than that of winter. Neglect the seasonal atmospheric pressure difference. [2 Pts]. Pg Pmix-Pg -[3 Pts], (b) From the definition of specific humidity (w) and relative humidity ($), derive w = 0.622 where Pix = mixture pressure & P = saturation pressure of water vapor at the mixture temperature. (c) Explain why the phase change of water in the mixture cannot be isothermal + isobaric during a constant heating of the mixture. Draw diagrams if needed [3 Pts].