Temperature shock
The temperature shock test is to determine if materiel can withstand sudden changes in the temperature of the surrounding atmosphere without experiencing physical damage or deterioration in performance. Sudden changes is an air temperature change greater than 10°C within one minute.
In a normal environment, this method is used when the requirements documents indicate that the materiel is likely to be deployed in conditions where it may experience sudden changes in air temperature.
This method is designed to evaluate the effects of rapid temperature shifts on the outer surfaces of materiel, items mounted on these surfaces, or internal components located near external surfaces. Essentially, this is a surface-level test. It typically addresses:
a. The transfer of materiel between climate-controlled areas and extreme external ambient conditions, such as moving from an air-conditioned enclosure to desert high temperatures or from a heated enclosure in cold regions to freezing outdoor temperatures.
b. Ascent from a high-temperature ground environment to high altitude via a high-performance vehicle (hot to cold only).
c. Air delivery or airdrop at high altitude and low temperatures from aircraft enclosures, when only the external material (packaging or materiel surface) is to be tested.
Air to air thermal shock chambers
Climatic chambers for thermal shock tests are used to subject the specimen to strong shocks by passing it suddenly and repeatedly from a hot temperature zone to a cold one. The specimen can cool or heat at different rates at different points, depending on the material. If exposure to repeated cycles cause large expansions and contractions in volume, the material could undergo strong mechanical stresses and sometimes break.
You can read more about thermal shock chambers here.