I spent time this week visiting family. While away, I collected several thermal observations of the clouds.
On November 20th in Colby, KS, the ground temperature was 26 *F and the cirrus clouds has a temperature was -59 *F. Assuming a dry adiabatic lapse rate of 5.4 *F, the clouds were at a height of 15,700 feet.
In Casper, WY, the ground had a temperature of 55 *F and the clouds a temperature of -29 *F. That indicated a height of 15,600 feet.
In Manhattan, KS, the ground temperature was 37 *F and the cirrus clouds had a temperature of -14 *F. That indicates a cloud height of 9,400 feet.