Atmospheric mixing adiabatic processes

It is important not to confuse this dry adiabatic lapse rate with the rate of change in temperature with height in a Standard Atmosphere. The latter represents average conditions in Earth s atmosphere, where heating, mixing, and wet adiabatic processes also are occurring. 

Ga.s-to-particie conversion may result from homogeneous gas-phase processes, or it may be controlled by processes in the particulate phase. Gas-phase processes, either physical or chemical, can produce a supersaturated state which then collapses by aero,s ol formation. Physical processes producing supersaturation include adiabatic expansion or mixing with coo air—-discussed in the last chapter—or radiative or conductive cooling. Gas-phase chemical reactions such as the oxidation of SO2 to sulfuric acid in the atmosphere or the oxidation of SiCU to SiOi in industry also generate condensable products. 

The container in Fig. 4.19 is initially evacuated. Then the valve is opened, and atmospheric air flows in, compressing the spring. The entire inflow and compression process is adiabatic. The temperature of the atmospheric air is 20 C. When the process is over, the volume of the contained air is 10 m its pressure is 1 atm, and the work done on the piston and spring system is 13 kJ. The air in the container is perfectly mixed. What is the temperature of the air in the container ... 

The space between the piston and the valve is now at an absolute pressure of zero. Outside the valve is the atmosphere. We now ojien the valve and let the air flow in. The process is adiabatic. There is sufficient mixing that the contents of the cylinder are always at a uniform pressure and temperature. What is the temperature of the air in the cylinder when the inflow of air stops ... 

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