A new study conducted by a scientist from the University of Bristol, Great Britain, shows that the atmospheric anomaly on Titan, the largest satellite of Saturn, recently reported, is associated with the unique chemistry of the atmosphere of Titan.
The atmosphere of Titan in the circumpolar region has recently experienced an unexpected and very deep cooling, which is contrary to the predictions made in the framework of modern models, as well as the behavior of all other terrestrial-type planets of the solar system.
Usually the atmosphere of the planet in the circumpolar region of the winter hemisphere is relatively warm, because the air coming down near the pole is compressed and heated by compression – just as it does in the bicycle pump when the wheel is pumped.
However, to the astonishment of scientists, the atmospheric vortex, located in the circumpolar zone of the surface of Titan, turned out to be very cold.
According to the main author of a new study by Dr. Nick Teanby from the School of Earth Sciences at Bristol University, the explanation for this phenomenon lies in the exotic chemistry of the atmosphere of Titan. On the Earth, Mars and Venus, the main contribution to the cooling of the atmosphere is made by infrared radiation emitted by molecules of carbon dioxide (CO2). Since carbon dioxide is very stable and well mixed with other gases at all levels of the atmosphere, its local concentration is almost not affected by atmospheric circulation. On Titan, exotic photochemical reactions in the atmosphere lead to the formation of hydrocarbons and nitriles, and these gases make the main contribution to the cooling of the atmosphere. These gases are formed high in the atmosphere of Titan, and their distribution exhibits a sharp vertical gradient, so that even a moderate vertical circulation of the atmosphere can substantially influence their local content. Therefore, the winter subsidence of air masses led to the enrichment of the Titan atmosphere in the circumpolar region by these gases actively emitting in the IR band and subsequent cooling of this zone due to intense radiation, Tinby believes.