Earth’s atmosphere has a history — not just in terms of temperature and composition, but also in the dynamics of its motions and chemistry. By tracing ultra-rare molecules in the present-day atmosphere and back into the past, Laurence Yeung , Assistant Professor of Earth Science at Rice University and recent Clarke Award recipient , is setting out to trace that dynamic history. “In the same way you'd tag a shark to figure out what its migration patterns are,” he explains, “you can exploit the natural tags that Mother Nature gives us in these stable isotopes.” Stable isotopes are atoms of the same element that differ slightly in mass thanks to an extra neutron or two, and they act as passive tracers in the atmosphere. A heavy isotope’s extra bit of mass can affect the physical and chemical processes it undergoes, concentrating or diluting it with respect to its lighter siblings. As a result, the ratio of these isotopes, like typical oxygen-16 (which has 8 protons and 8 neut
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