Tropopause Variations and Cyclogenesis

A dip in the tropopause accompanies an upper tropospheric cyclone, which induces southerly winds at the surface bringing warm air from the tropics.

Schematic 3D image of the tropopause as a constant PV surface. A dip in the tropopause accompanies a strong upper-level cyclonic circulation, which may reach the surface. The southerly wind on the east side of this surface cyclone brings warm air northwards from the tropics.

Warm air brought from the south at the surface induces a surface cyclone.

Schematic 3D image of the warm surface air.
Circulations associated with the surface cyclone propagate upward with decreasing magnitude.

When an upper-level cyclone meets warm surface air, a strong cyclone extending throughout the tropopause develops.

Schematic 3D image of a low tropopause and warm surface air.
Because of superposition, the cyclone is enhanced and extends throughout the troposphere.