Observations of freezing planetary atmospheres

The planet which has a cold climate may experience freezing of its atmosphere. In the solar system, Mars is one of the planets having the atmosphere freezing. The amount of freezing atmosphere in the Martian polar night reaches 20-30% of the total amount, significantly affecting the Martian climate. The freezing of the Martian atmosphere has been investigated by temperature measurements, such as infrared measurements and radio occultation measurements. In the presentation, we review those measurements and scientific targets in the past, which will contribute to the discussion on the small-satellite based observations of the planetary climate.