A study of special and routine data during the passage of two winter synoptic disturbances through the Woomera (lat. 31°s) area has revealed the following features. A barotropic "trowal" is found at least in low levels, between two baroclinic zones, which may broadly be called, respectively, warm and cold frontal zones. The cold frontal zone is quite broad but embedded within it may be a concentrated line or lines of rapid change of temperature, wet bulb temperature or wind. The wind shear line does not necessarily occur at the "front" of strong density contrast, and changes in wind, temperature and wet bulb potential temperature in low levels may be masked at the surface by a low level inversion, so that "overrunning" of these changes may appear. The air mass boundary exhibits a different shape from that of the "front" as defined in terms of density contrast. It is affected by the middle level prefrontal cloud mass, which in turn is conditioned by ascending motions preceding (katafront) or both preceding and following (anafront) the surface frontal pas sage. The low level jet is a nocturnal and morning phenomenon found approximately at the top of the low level inversion, and in the cases studied was topped by a layer of wind veering with height. The relation between change of wind direction with height and temperature advection is shown to be roughly as accounted for by inviscid theory except in the low levels du ring inversion conditions.
T. Kamiko (Tue,) studied this question.