instability line

Any nonfrontal line or band of convective activity in the atmosphere; this is the 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 termed a squall line; therefore, in practice, instability line often refers only to the less active phases.

Related terms:

• prefrontal squall line
• potential instability
• absolute instability
• pressure-jump line
• baroclinic instability
• convective instability
• mechanical instability
• autoconvective instability
• squall line
• line squall