visual2.gif (3763 ???) Visualization and WKB analysis of the internal gravity wave in the QBO experiment ????-?????? ??-??????

Another method visualizes the internal gravity wave using the moíre method. This method utilizes the property of light that passes horizontally through a stratified fluid is refracted to the opposite direction of the density gradient. This method is much more inexpensive than the Shrearen method.

In principle, when a stripe image distorted by the density disturbance is overlaid with an undistorted image, moíre stripes appear showing the pattern of the internal gravity wave.6)  In this experiment, however, the curvature of the tank also distorts the image, and therefore, a simple application of this method produces moíre stripes even when the working fluid is at rest. For this reason, instead of using an undistorted image, a distorted image of the stripe pattern is overlaid with an image in a different phase. This overlaying process was performed with a computer after scanning the recorded film.

souti1s.gif (2507 ???)

Figure 3 Top view of the photography system