This is the first time a movie sequence of Jupiter has been made that illustrates the motions of the high-altitude clouds on a global scale. 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.
Jupiter's equator and Great Red Spot are covered with high-altitude, hazy clouds. Features in this methane-filter movie appear more diffuse. Among the nearly stationary features are the Red Spot and some bright ovals at mid-latitudes in both hemispheres. They are bright in the methane band because of their high clouds associated with rising gas. They behave differently from terrestrial cyclones, which swirl in the opposite direction.