6-022. Assume a cloud is based at 3,000 feet AGL, where the temperature at this altitude is 3º C. Based on adiabatic lapse rates, at what height would the freezing level be found at?
6-022 (Answer). The freezing level under these conditions would be found at 5,000 feet AGL. From the cloud base upwards, the air is saturated, therefore, we would use the Saturated Adiabatic Lapse Rate of 1.5º C/1,000 feet to find the height of the freezing level. Applying this lapse rate from the cloud base would require a drop in temperature of 3º to reach the freezing level, and 3º C/1.5º C per 1,000 feet = 2,000 feet. Adding 2,000 feet to 3,000 feet = 5,000 feet AGL freezing level. [Ref: ATP GSC s. 6.04]