| Abstract: Symmetries and topology are central to our understanding of physical systems. Topology, for instance, explains the precise quantization of the Hall effect and the protection of surface states in topological insulators against scattering from disorder or bumps. However discrete symmetries and topology have not, until recently, contributed much to our understanding of the fluid dynamics of oceans and atmospheres. In this talk I show that, as a consequence of the rotation of the Earth that breaks time reversal symmetry, equatorial Kelvin and Yanai wavesemerge as topologically protected edge modes. The non-trivial topology of the bulk Poincaréwaves is revealed through their winding number in frequency - wavevector space. Bulk-interface correspondence then guarantees the existence of the two equatorial waves. I discussour recent direct detection of the winding number in observations of Earth’s stratosphere.Thus the oceans and atmosphere of Earth naturally share basic physics with topologicalinsulators. As equatorially trapped Kelvin waves in the Pacific ocean are an importantcomponent of El Niño Southern Oscillation, the largest climate oscillation on time scales of afew years, topology plays a surprising role in Earth’s climate system. We also predict thatwaves of topological origin will arise in magnetized plasmas. The waves may appear inlaboratory plasma experiments, and they may also arise in the solar system and beyond. |