Hemispheric differences in general decrease with increasing altitude.  All the jet streams of the Northern Hemisphere have their southern analogues.  Southern jets are more intense on the average with smaller amplitudes, reflecting the greater zonal indices (over double in magnitude) of this hemisphere.  The stratospheric cyclone of the polar night transforms into the anticyclone of the polar day in both hemispheres, but the explosive warming prior to the onset of the polar day has not yet been observed over the Antarctic. Blocks are comparatively rare and occur southeast of continents in late winter and early spring, and drift slowly eastward again emphasizing the importance of middle latitude continents on features of the general circulation. There is some doubt as to whether counterparts of the Aleutian and Icelandic lows exist in the mean circulation of the Southern Hemisphere.  If they do, they are located in the Ross and Weddell Sea areas, on the edge of Antarctica, and are most sharply defined at about 700 millibars.  Navy meteorologists with experience in those areas indicate that many lows undergoing cyclolysis move into these regions but disappear rapidly at low levels, retaining their identity as cold lows aloft for longer periods.
