"waves beneath the sea" phenomenon physics field experiment teaching aspects
TRANSCRIPT
"Waves beneath the Sea"
Phenomenon
Physics
Field Experiment
Teaching Aspects
Dan KelleyOceanography Dept.Dalhousie University
http://www.phys.ocean.dal.ca/~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=gDr/r
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