instability line

(No longer frequently used.) Any nonfrontal line or band of convective activity in the atmosphere.

It is a general term and includes the developing, mature, and dissipating stages. However, when the mature stage consists of a line of active thunderstorms, it is properly called a squall line; therefore, in practice, instability line often refers to the less active phases.
See also pseudo front, prefrontal squall line
Fulks, J. R. 1951. Compendium of Meteorology. 647–652.

(No longer frequently used.) Any nonfrontal line or band of convective activity in the atmosphere.

1. The study of the physics, chemistry, and dynamics of the earth's atmosphere, including the related effects at the air–earth boundary over both land and the oceans. Fundamental topics include the composition, structure, and motion of the atmosphere. The goals ascribed to meteorology are the complete understanding and accurate prediction of atmospheric phenomena.