Harlan Spence (UNH), Q: Precipitation, Kelvin-Helmholtz Waves, and Turbulence - Atmospheric Science or Space Science? A: Both!

November 14, 2018 3:30pm
MSA 7124


Space plasma physics borrows not only many terms from its older sister, atmospheric physics, but also the fundamental physical processes that these words describe.  While the space environment seems remote and hence mysterious, the complex behavior of geophysical fluids that permeates our lives on Earth is nevertheless somewhat intuitive to most people probably because of its familiarity.    When it rains or snows, we experience precipitation.  When we see amazing cloud formations in the sky, we can imagine the wind shears that produce them.  When we fly in an airplane or look at vortices that form and dissipate in a swimming pool, we directly experience and visualize the process of turbulence.  Of course, experiencing these processes only provides a crude sense of why and how they might occur.  It took over a century of scientific research in geophysical fluid dynamics and atmospheric physics to reveal the amazing richness of these scientific processes associated with the collisional fluids of our oceans and atmosphere.  In space, many of these same processes occur, but in this case in a magnetized, weakly-collisional plasma with extra terms in the governing equations.  In many cases, these space plasma phenomena look remarkably familiar to analogs on Earth, while in other cases only the words that describe the phenomena are remotely the same.  In this talk, I discuss examples of precipitation, KH waves, and turbulence in space plasmas and how these phenomena both unite space physics with atmospheric and ocean science and also differentiate it from them.