Variation of intensity of low pressure areas with height

The temperature structure associated with surface low pressure systems allows us to DIAGNOSE the pressure patterns aloft directly above them. (Careful: this does NOT answer the question about WHY such lows form).

1. Cold core surface lows strengthen with height. This can be understood by applying the concept of the hypsometric relation to such a low, viewed in cross-section. This means that the pressure gradients around their centers intensify with height (at a given contour gradient, there will be more isobars or height contours around the center. Here's a case from October 11, 2015: 850 mb, 700 mb, 500 mb, 250 mb. Some examples of such lows include cut-off lows and occluded lows. However, cold core lows (by definition) are barotropic, meaning that height contours and the geostrophic wind are parallel to isotherms and there can be no temperature adveciton.

2. Warm core lows weaken with height and are replaced by flat pressure gradients or high pressure areas aloft. This can be understood by applying the concept of the hypsometric relation to such a low, viewed in cross-section. Some examples of such surface lows include hurricanes, the continental thermal lows during the summer time. However, warm core lows (by definition) are barotropic, meaning that height contours and the geostrophic wind are parallel to isotherms and there can be no temperature adveciton.

3. Lows with assymetric temperature distributions do not largely change intensity with height, but are tilted towards the cold air. In other words, the centers of the lows are found progressively further "back" into the cold air.This can be understood by applying the concept of the hypsometric relation to such a low, viewed in cross-section. Wave cyclones are an example of such a surface low. However, lows with assymetric temperature distrbutions (by definition) are baroclinic, meaning that height contours and the geostrophic wind are at angles to isotherms and there IS significant temperature advection.