ACTIVITY 15.8 Adiabatic Processes and Cloud Formation Figure 15.10 shows air that begins with a temperature of 25°C and a relative humidity of 50 percent flowing from the ocean over a coastal mountain range. Assume that the dew-point temperature remains constant in dry air (relative humidity less than 100 percent). When the air parcel becomes saturated, the temperature and dew-point temperature become equal. As the air continues to ascend, the temperature and dew-point temperature will decrease at the wet adiabatic rate, but the dew-point temperature does not change as the air parcel descends. (Completing Figure 15.10 may be helpful.) 1. Use Table 15.2 to determine the saturation mixing ratio, water-vapor content, and dew-point temperature of the air at sea level in Figure 15.10. Saturation mixing ratio: 10 g of air 10 15 Water-vapor content: Dew-point temperature: 2. Is the air at sea level saturated or unsaturates? unsaturated Temp. Dew pt. D. 3000 m Temp. Temp. Dew pt. Dew pt. E. С. 2000 m Temp. Temp. Dew pt. F. Dew pt. 1000 m Temp. Dew pt. Temp. Dew pt. G. Temp. at Point A = 25°C Relative humidity at Point A = 50% Dry adiabatic rate = 10°C/1000 meters Wet adiabatic rate = 5°C/1000 meters A. Sea level A Figure 15.10 Adiabatic processes and cloud formation associated with air being lifted over a mountain barrier.