We Finally Know Why Titan's Polar Vortex Is Freakishly Cold

Wednesday, 22 November 2017 - 1:03PM
Wednesday, 22 November 2017 - 1:03PM
We Finally Know Why Titan's Polar Vortex Is Freakishly Cold
Image credit: NASA
Saturn's massive moon Titan has a weather pattern unlike anywhere else in the Solar System.
 
Other worlds, including ours, have polar vortices, areas of low pressure, churning cold air that take place in polar regions.

We here on Earth know ours personally, as it can send sub-zero temperatures our way. However, this activity involves the sinking of air, causing it to compress and heat up, meaning higher layer of the atmosphere over polar regions actually warm up.
 
Except on Titan, that is.


 
The Saturnian moon is the only moon in the Solar System to have a substantial atmosphere, and the Cassini–Huygens mission (before ending in September this year) had been studying Titan among its other duties monitoring Saturn and its satellites.

In August 2009, Cassini gave researchers a look at the formation of an anticipated hot spot in the atmosphere.

By 2012, the hot spot was gone, and a cooler region had developed, clocking in at a not-quite-toasty temperature of -153°C (-243°F).

This polar vortex was detected until late 2015, followed by observations in 2016 and 2017 that the hot spot had returned.


 
Scientists working on Titan's titanic weather weirdness believe they have worked out this one-of-a-kind event, and put the blame on its unique atmospheric configuration.
 
An international team of researchers might have finally worked out why Titan's winter polar vortex behaves unlike any other in the solar system. The team thinks it's all due to Titan's peculiar atmospheric composition.
 
Dr. Nick Teanby of the University of Bristol's School of Earth Sciences explains that on Earth, Mars and Venus, the main mechanism of atmospheric cooling is infrared radiation produced by CO2, which is well-integrated throughout the atmospheres, and isn't really affected by circulation, but, as he recently told the University of Bristol, "On Titan, exotic photochemical reactions in the atmosphere produce hydrocarbons such as ethane and acetylene, and nitriles including hydrogen cyanide and cyanoacetylene, which provide the bulk of the cooling."
 
Via Cassini, the researchers measured temperature and gas quantities, and then compared the data to a model of heating and cooling rates, finding that the gas enrichment was significant enough to cause the extremely cold temperatures in the atmosphere.
 
Teanby added: "This effect is so far unique in the solar system and is only possible because of Titan's exotic atmospheric chemistry…A similar effect could also be occurring in many exoplanet atmospheres having implications for cloud formation and atmospheric dynamics."
Science
NASA
We Finally Know Why Titan's Polar Vortex Is Freakishly Cold