Rising, unsaturated air (relative humidity less than 100%) expands and cools at a rate of9.8 C° per 1000 m(5.5 F° per 1000 ft). This is called the dry adiabatic lapse rate. What is the dry adiabatic lapse rate per km? The dry adiabatic lapse rate (abbreviated DALR) is 5.5°F ...