On the theory of frontal surfaces not in contact with the ground

The theoretical models of frontal zones situated aloft and not reaching the ground are discussed. Only mature fronts, for which a dynamic balance between frontogenetical and frontolytical processes has been achieved, are considered. The motion of air in the system of cold and warm air masses is studied and a transition (inversion) layer between those masses of different densities is replaced by a surface of discontinuity (frontal surface) which is assumed not to intersect the ground but become horizontal ("free front"). Physical factors influencing the free front motion are discussed, and different formulations of the free front problems that allow obtaining analytical solutions are suggested.