A ripple, eddy current, or “disturbance” in the upper or mid-level atmospheric flow that causes lifting and sinking of the air.

Some weather parameters that capture these disturbances are vorticity and vertical velocity pressure. On upper air charts, short waves appear as a wave or large ripple in the isopleths, and when especially prominent at 700 mb (~10,000 ft), they are associated with precipitation when humidity is also high at 700 mb