QBO

Observing internal gravity waves

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(Animation GIF)
Internal gravity wave with
no mean current


(Animation GIF)
Internal gravity wave
distorted by a mean current


(Animation GIF)
Pattern change of
the internal gravity wave
due to a mean current
wave period:
amplitude: 		15 sec
10 mm
wave period:
amplitude:
 16 sec
13 mm

The mean current flows from right to left just below the membrane.
wave period:
amplitude:
15.7 sec
13 mm

The period of reversing currents is approx. 75 min.
When a current occurs, the waves heading to the right and
those heading to the left become stronger alternately.

Experimental conditions

Brunt-Väisälä period : 3.9 sec
The amplitude of the membrane was measured at the center of the membrane.

Photographic conditions

f=135mm,F32,ASA400,red and blue strobes are used.