First Chapter of the Northern Storm
Date: 11 Jan 2011
This mosaic of false-color images from NASA's Cassini spacecraft shows what a giant storm in Saturn's northern hemisphere looked like about a month after it began. The bright head of the storm is on the left. The storm also spawned a clockwise-spinning vortex, seen as the light blue circular feature framed with a curl of bright clouds a little to the right of the storm head.
Cassini's imaging camera obtained the images that went into this mosaic on Jan. 11, 2011. The storm erupted in early December 2010 and the head of the storm began moving rapidly westward. The vortex, spun off from the head of the storm in early December shortly after the storm began, drifted much more slowly. In August 2011, the head ran into the vortex, like a version of the mythical serpent that bites its own tail. By late August, the convective phase of the storm was over.
The colors indicate the altitudes of the clouds - red is the lowest, green is an intermediate level and blue is the highest. White indicates thick clouds at a high altitude. Scientists assigned red to a wavelength of radiation that penetrates the atmosphere deep down to the top of the tropospheric cloud deck (750 nanometers). The troposphere is the part of the atmosphere where weather occurs. They assigned green to the 728-nanometer wavelength. Blue is a wavelength band that penetrates only to the top of tropospheric haze (890 nanometer).
Credit: NASA/JPL-Caltech/SSI/Hampton University