Organized wind systems occur in spatial dimensions ranging from tens of metres to thousands of kilometres and possess residence times that vary from seconds to weeks. The concept of scale considers the typical size and lifetime of a phenomenon. Since the atmosphere exhibits such a large variety of both spatial and temporal scales, efforts have been made to group various phenomena into scale classes. The class describing the largest and longest-lived of these phenomena is known as the planetary scale. Such phenomena are typically a few thousand kilometres in size and have lifetimes ranging from several days to several weeks. ...(100 of 37038 words)