An
upper tropospheric cyclonic vortex is a
vortex, or a circulation with a definable center, that usually moves slowly from east-northeast to west-southwest and is prevalent across
Northern Hemisphere's warm season. Its circulations generally do not extend below in altitude, as it is an example of a
cold-core low. A weak inverted
wave in the
easterlies is generally found beneath it, and it may also be associated with broad areas of high-level clouds. Downward development results in an increase of
cumulus clouds and the appearance of
circulation at ground level. In rare cases, a warm-core cyclone can develop in its associated convective activity, resulting in a
tropical cyclone and a weakening and southwest movement of the nearby upper tropospheric cyclonic vortex. Symbiotic relationships can exist between tropical cyclones and the upper level
lows in their wake, with the two systems occasionally leading to their mutual strengthening. When they move over land during the warm season, an increase in
monsoon rains occurs.