Tangential acceleration

From Glossary of Meteorology

tangential acceleration

The component of the acceleration directed along the velocity vector (streamline), with magnitude equal to the rate of change of speed of the parcel dV/dt, where V is the speed.

In horizontal, frictionless atmospheric flow, the tangential acceleration is balanced by the tangential pressure force,
where α is the specific volume, p the pressure, and s a coordinate along the streamline. Thus, flow without tangential acceleration is along the isobars, and the wind is the gradient wind.