"Waves beneath the Sea" Phenomenon Physics Field Experiment Teaching Aspects
Dan Kelley Oceanography Dept. Dalhousie University ~kelley/ papers/ presentations/ 2001/ AST
"Dead" water Boat slows to a crawl surfing internal wake Nansen observation 189x Ekman explanation 1904
External and Internal Waves: restoring forces External waves: gravity g Internal waves: reduced gravity g=g / 0
Physics of Waves Restoring force key to all oscillators!
Class Experiment [1]
Class Experiment [2]
Internal Waves in Atmosphere [1] Wave crests... rising air... condensation clouds.
Internal Waves in Atmosphere [2]
Banded Surface Slicks Convergent zones over troughs Sweeps oil into lines Visible by eye, radar, satellite, etc.
Ocean from Airplane
Ocean from Space
Ship Radar Internal waves yield banded slicks banded roughness surface signature of internal waves
SurfaceTidal Bore
Physics of (Tidal) Bore
Other Surface Bores [1]
Other Surface Bores [2]
Peter Galbraith PhD at Dalhousie Mixing, internal waves, estuarine physics Works at DFO in Quebec
Internal Tidal Waves
Chopper - a new type of ship!
Daniel Bourgault PhD at McGill Estuarine physics, ocean modelling, internal waves Works with me at Dalhousie
St. Lawrence Est. Internal Wave
Modelled Internal Wave
View from Shore
St. Lawrence Estuary
Geometrically Corrected View
Enhanced View
Internal Waves on Rotating Planet Wave "phase" goes one way wave "energy" goes another! Important to climate...
Scientific Summary Ocean/atmosphere has internal as well as external waves These waves may break causing ocean mixing affecting biology,... affecting chemistry,... affecting climate...
Teaching Summary Explains cloud patterns Explains "dead water" Illustrates universality of Physics (here, across Ocean & Atmosphere) Illustrates idea of restoring force Illustrates resonance