Stratiform

Stratiform is an adjective used in geology and meteorology to describe objects, formations, or deposits that are formed in or resemble layers. The word derives from Latin stratus, meaning layer, and forma, meaning shape or form.

In meteorology, stratiform clouds are extensive, horizontally uniform cloud sheets that form in relatively stable air with weak vertical motion. They contrast with cumuliform clouds, which are more vertically developed and billowy. Common stratiform cloud types include stratus, stratocumulus, altostratus, and nimbostratus. They typically produce widespread, light to moderate precipitation such as drizzle or steady rain, and they can lead to prolonged overcast skies and fog. Formation mechanisms involve gradual lifting and cooling of air over large areas or the spreading of moisture through broad fronts rather than localized convection.

In geology and economic geology, stratiform describes ore bodies and rock units that occur in roughly parallel, layered sheets. Stratiform ore deposits form from the deposition and precipitation of minerals within sedimentary basins or volcanic-sedimentary sequences, resulting in continuous, laterally extensive beds that are relatively uniform in thickness and grade. Notable examples include banded iron formations and certain sedimentary exhalative deposits. Stratiform rocks are typically distinguished from intrusive or structurally controlled deposits by their planar geometry and repeating layering in the stratigraphic record.

The term is also used more broadly in other disciplines to indicate layered or plate-like forms. Across domains, stratiform conveys a sense of organization by layers rather than by vertical differentiation.