In the Geophysical Fluid Dynamics Lab he helped establish at WHOI, Jack Whitehead sets up experiments that effectively simplify complicated processes down to the fundamental forces of physics that generate them. In this case, colored dyes help track the flow of distinct water masses on a rotating table, which simulates the force caused by Earth's rotation.
The Geophysical Fluid Dynamics Lab at WHOI is a nexus for scientists exploring, and teaching, the basic principles of how fluids move on the dynamic Earth. "We not only make the experiments to teach ourselves, but also to learn together with others," said Whitehead, examining an experiment with visiting student Tomasso Ascarelli (right).
In the 1970s, Whitehead partitioned a container of fresh water into two basins. He mixed in salt and black dye on one side (left), representing the salty Mediterranean Sea; the clear, fresh water on the right side represented the much less salty Atlantic Ocean. The basins were connected by a narrow channel (the Strait of Gibraltar), blocked by a sliding door. Whitehead steadily rotated the entire apparatus to simulate Earth's rotation, and when he slid open the door, a gyre of clear water spiraled clockwise out of the narrow chute onto the surface of the idealized Mediterranean. The experiment solved the mystery of why the real-life Alborán Gyre forms in the western Mediterranean.
In the early days of the plate tectonic theory, Whitehead devised an experiment heating fluids with different viscosities in plastic containers to simulate hot material in Earth's mantle. Thin, worm-like streams of less dense fluid rose buoyantly within denser fluid toward the top and expanded outward like balloons at the end of straws. The experiment demonstrated how “mantle plumes” form. The plumes can cause hard ocean crust above them to spread apart, forming a chain of volcanic mountains between diverging tectonic plates.
WHOI physical oceanographers Karl Helfrich (left) and Claudia Cenedese (striped sweater) demonstrate to student visitors how denser waters sheet down slanted surfaces (such as, on a larger scale, a continental slope). Whitehead has collaborated with Cenedese to study eddies—swirling masses of water that are pinched off currents and remain intact as they travel through the oceans. With Helfrich, he has explored solitons—a solitary waves, or pulses of water, that can travel long distances through fluids, maintaining their shapes and speeds. The phenomenon occurs in water and in light.
At a celebration for the 50th anniversary of the Geophysical Fluid Dynamics Program at WHOI in 2008, Jack Whitehead (trombone) joins a trio with accordionist Raymond Pierrehumbert, the Louis Block Professor in Geophysical Sciences at the University of Chicago, and trumpeter Bob Katcher, a systems analyst at WHOI.