The nature of symmetric instability and its similarity to convective and inertial instability.

Abstract

It is shown that there exists a local similarity among SI (symmetric instability), BI (buoyancy or convective instability), and II (inertial instability) even for fully nonlinear viscous motion. The most unstable slope angles for SI are analyzed through a consideration of parcel energetics, and this suggests that qualitatively CSI (conditional SI) circulations will be slantwise and lie between the moist most unstable and dry least stable slopes of the basic state. -Authors