Among Georg Wüst's many contributions to oceanography are his almost pole-to-pole meridional sections of the Atlantic Ocean (Wüst, 1935). Figure 5.1 here shows his “main” or western section, forcefully making the point that most of the ocean waters are cold, excepting only a shallow surface pool from about latitude 52°N to 43°S. The bottom of the warm pool is the 8°C isotherm according to Wüst's choice, but the 10°C, or 5°C, one serves just as well. The depth of the warm water varies from 200 m at the equator, to 1000 m at the center of the “subtropical gyre” in the North Atlantic. Wüst called this the “Warmwassersphäre,” or alternatively the Troposphere, versus the deeper Stratosphere. The latter terminology is less apt, the troposphere analogy being somewhat forced. In English, WarmWaterSphere is gratifyingly descriptive, and the acronym WWS fits both saxon tongues.

The influence of the WWS on the climate of continents, especially coastal regions, is pronounced. Trondheim, Norway is a pleasant place to visit in summer, with 24 hours of daylight, and no need for a coat while walking home from a party. At the same latitude South, at the northern tip of the Antarctic Peninsula, nobody lives. The difference is that the annual mean sea surface temperature off Trondheim is 8°C, at the northern limit of the WWS, versus -1°C off Antarctica, the 8° isotherm being there 1500 km away equatorward.