Warm colors represent regions of net melt and cool colors are regions of active ice growth.
This image shows that sea ice formation and decay processes can occur simultaneously in the same polar region. Sea ice distribution in the polar regions became much better understood with the successful remote sensing of the polar regions by satellites using passive microwave radiometers. The harsh conditions of the polar latitudes have historically made sea ice a difficult subject for scientific study. Prior to the 1970's, the lateral extent and temporal resolution of sea ice distribution was poorly understood. Satellites, prior to the advent of passive microwave imagery, did detect sea ice by analyzing visible and near infra-red radiation from Earth's surface.