Answer to Question B.1 Yielding Perfect Score

The weather system that serves as the basis for the exam is a typical baroclinic system. Note on the above figure that the surface disturbance is a wave cyclone with moderate to strong temperature warm (cold) advection ahead (behind) the warm (cold) fronts. The line labeled A to B is at roughly right angles to the cold front and intersects the surface disturbance.

Plotted along this line are the positions of the surface, 850 mb, 700 mb, 500 mb and 200 mb disturbances. Note that the centers fo the lowest pressure are found progressively further west into the colder air (as indicated by the lower thickness values). Thus, this system tilts into the colder air.

A simple application of the hypsometric relation explains why this occurs in this case (and for all baroclinic lows). A cross section along line A to B would show that the thicknesses between isobaric levels are greater in the warm air (near B) than at A. Since isobars are concave upwards in low pressure areas or troughs, this implies that at progressively higher elevations the center of lowest pressure is displaced towards the coldest air, as shown in the diagram below.