These Multi-angle Imaging Spectroradiometer (MISR) images from June 11, 2000
demonstrate a turbulent atmospheric flow pattern known as the von Karman vortex
street. This phenomenon is named after aerodynamicist Theodore von
Karman, who theoretically derived the conditions under which it occurs.
The alternating double row of vortices can form in the wake of an
obstacle, in this instance the eastern Pacific island of Guadalupe. The
rugged terrain of this volcanic Mexican island reaches a maximum
elevation of 1.3 kilometers. The island is about 35 kilometers long and
is located 260 kilometers west of Baja California.
The vortex pattern is made visible by the marine stratocumulus clouds
around Guadalupe Island. The upper image is a color view obtained by
MISR's vertical- viewing (nadir) camera. North is toward the left. The
orientation of the vortex street indicates that the wind direction is
from lower left to upper right (northwest to southeast). The areas
within the vortex centers tend to be clear because the rotating motions
induce a vertical wind component that can break up the cloud deck.
The lower view is a stereo picture generated from data acquired by
MISR's fore- and aft-viewing 70-degree cameras. A 3-D effect is obtained
by viewing the image with red/blue glasses and placing the red filter
over your left eye. Note how the downwelling atmospheric motion (change
in elevation from high to low) is accompanied by a clearing in the
center of the first vortex. As the vortices propagate downstream, their
rotational velocities weaken. As a consequence, the induced vertical
motion and cloud-clearing effect weakens as well.
Theodore von Karman was a Professor of Aeronautics at Caltech and
Director of Caltech's Guggenheim Aeronautical Laboratory from 1930-1949.
He was one of the principal founders of the Jet Propulsion