Air-sea interaction in the middle latitudes is scale-dependent. At horizontal scales of 100km or larger, which is the typical grid-size for global climate models, atmospheric forcing of oceanic variability tends to dominate at the air-sea interface. On smaller spatial scales, the forcing of the atmosphere by oceanic eddies becomes the dominant signal at the air-sea interface. This scale dependence is evident in the statistical correlation between sea surface temperature (SST) and surface wind speed, which tends to be negative at larger spatial scales, because strong atmospheric winds tend to cool the ocean. On smaller spatial scales, however, the correlation tends to be positive, as the oceanic eddies alter the atmospheric boundary layer.