The outer two of the white storms formed in the late 1930s. In the centers of these cloud systems the air is rising, carrying fresh ammonia gas upward. New, white ice crystals form when the upwelling gas freezes as it reaches the chilly cloud top level where temperatures are -130�C (-200�F). The intervening white storm center, the ropy structure to the left of the ovals, and the small brown spot have formed in low pressure cells. The white clouds sit above locations where gas is descending to lower, warmer regions.