This type of analysis stresses not the large air masses but the smaller scale concentrated airflows that determine the cloud and precipitation and the structure and evolution of the cyclone. It is carried out within isentropic surfaces in a coordinate frame traveling with the weather system. Cold conveyer belt - air ahead of and beneath the warm front which, relative to the advancing system, flows rapidly rearward around the polward side of the low center. Dry Intrusion - a stream of air from the upper troposphere and lower stratosphere, which, after earlier decent, approaches the center of the cyclone as a well defined reascending dry flow with low q w . First, it must be stressed that it is not the intent here to infer dynamic similarity of the ETC and mesocyclone in the strict sense of the term.
Mesoscale flows are substantially ageostrophic and nonhydrostatic and definitely three-dimensional.
Nevertheless, the many resemblances suggest physical concepts which link these vortical flows. Here, we can only summarize the similarities due to space considerations . Figure 2 . Schematic plan view of a supercell storm at the surface. Thick lines encompasses radar echo.