1. In meteorology, an elongated area of relatively high atmospheric pressure, almost always associated with and most clearly identified as an area of maximum anticyclonic curvature of wind flow. The locus of this maximum curvature is called the ridge line. Sometimes, particularly in discussions of atmospheric waves embedded in the westerlies, a ridge line is considered to be a line drawn through all points at which the anticyclonically curved isobars or contour lines are tangent to a latitude circle. The most common use of this term is to distinguish it from the closed circulation of a high (or anticyclone); but a ridge may include a high (and an upper-air ridge may be associated with a surface high) and a high may have one or more distinct ridges radiating from its center. The opposite of a ridge is a trough. 2. Also used as reference to other meteorological quantities such as equivalent potential temperature, temperature, and mixing ratio. That is, an elongated area of relatively high values of any particular field emanating from a maximum. 3. In oceanography, a linear accumulation of broken ice blocks projecting upward, formed by ice deformation, often at the edge of a floe. A ridge is distinguished from a hummock by being much longer than it is wide. The term ridge is often used to describe an entire ridged ice feature, in which case the portion above the water line is termed the sail and the portion below the water line is termed the keel.