John Wettlaufer       [website]

The formation of sea ice in the polar oceans plays a major role in the forcing of the Earth's climate. Sea ice extent varies by 6 million km2 in the Arctic and by 18 million km2 in the Antarctic. This solidification of saline ocean water leads to the expulsion of salty brine, the density of which is a driving force for large-scale oceanic currents. The micro-physical processes involved in the solidification of sea water (or in fact any binary solution) control both the rate of solidification and the rate at which brine is expelled, thus effecting the forcing of oceanic currents.

John S. Wettlaufer studies the physics of ice crystal growth and melting, and also conducts theoretical and experimental investigations of sea ice thermodynamics and air-sea-ice interactions.

The Yale Program in Solar and Terrestrial Physics (STP) is a joint program between the Yale Geology/Geophysics and Astronomy departments to study the physical mechanisms common to the Sun and Earth that govern their changes over time.

Unresolved questions range from long-standing paradoxes in Earth history, to pressing problems of the present day. For example, our best current theories of stellar evolution predict that the Sun was about 30% weaker early in Earth's history than today. Theories of Earth's climate indicate that with so little solar heating, the Earth should have frozen over. Yet somehow the Earth's climate has remained, if not constant, at least equable for life for nearly four billion years. We currently do not have a satisfying explanation for this "faint young sun" paradox. We are also struggling with a problem on much shorter timescales---the prediction of how climate will change in the coming decades due to human alteration of the composition of Earth's atmosphere. Terrestrial climate is a rich and very challenging problem that requires deep understanding, but also creativity, to overcome the obstacles of studying a bafflingly complex, dynamical system.

The joint STP program is an unique collaborative effort between a space sciences and Earth sciences department, poised to exploit the growing convergence between key elements of the study of the Sun and Earth. The core mission of this program is to attract and educate new graduate students who will have the fluency across disciplines to generate the new discoveries that will become possible.

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