It was taken in early October 2000. So, dark areas are relatively free of high clouds, and the camera sees through to the methane in a lower level.
Bright areas are places with high, thick clouds that shield the methane below.
The area shown covers latitudes from 50 degrees north to 50 degrees south and a 100-degree sweep of longitude. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.