The equatorward bending of height contours for the 500 mb level imply the presence of a trough because this represents a region of overall lower heights. A valley and a trough are hence equivalent in the upper air flow.
A trough is a linear structural depression with lateral length that occurs in geology. A trough can be a small basin or a natural rift, albeit it is lower than a trench. At the edge of tectonic plates, these landforms frequently form.
Trough, an extended depression in the seafloor that differs from oceanic trenches in that it is shallower, shorter, narrower, and topographically more mild. The Papuan Trough's maximum depth is 2,300 m (7,500 feet), while the Banda Trough's maximum depth is 7,440 m.
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