In The Field

AAS DPS 2008: Methane monsoon

titan.jpg Lots of weather-related Titan talks at this DPS, and it’s no surprise, coming from a confluence of maturing Cassini science and an approaching equinox. Titan, which has a year of 30 Earth years, had its summer solstice in 2002. In the next couple years, its north pole will heat up (relatively speaking) as it emerges from winter, and the prevalent methane and ethane lakes will begin to evaporate as clouds form and carry moisture in a giant convective cell that stretches from pole to pole. Pictured here is a Cassini snap from February, with a streaky cloud visible near the north pole: an early sign of spring. “The weather patterns are likely to change fairly rapidly, and that could be quite exciting,” says Ralph Lorenz of Applied Physics Lab in Maryland. The polar lakes grow in winter and shrink in summer, the thinking goes. Ralph points out that sci-fi master Arthur C. Clarke had that same thought back in 1976 in “Imperial Earth”. “It was sort of prophetic, in a way,” he says. An excerpt, courtesy Ralph:

The most impressive meteorological phenomenon was the so-called ‘Methane Monsoon’, which often – though not invariably – occurred with the onset of spring in the northern hemisphere. During the long winter, some of the methane in the atmosphere condensed in local cold spots and formed shallow lakes, up to a thousand kilometers square but seldom more than a few meters deep …

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