The CFDC's are used at colder temperatures to study the freezing behavior of solution drops and heterogeneous ice nucleation mechanisms at conditions representative of the upper troposphere. This figure shows the same type information as the previous one , but is in a colder regime. The set points are labeled as relative humidity instead of supersaturation. Thus, with the walls at -55C and -42.5C, the sample experiences -50C and 80% rh.