• Isentropes:
  A vertical cross section taken across the Cold Front - Thickness Ridge Cloudiness - Warm Front shows the typical frontal gradient of isentropes connected to the Cold Front and Warm Front. In between a maximum of isentropes is observed in the area of the Thickness Ridge Cloudiness. This maximum is an indication of a tongue of warm air. It consists of a maximum of closed isolines in the lower layers indicating unstable conditions. The height of the maximum differs according to the seasons and can be very extreme in summer. The upper part over the maximum has some similarities with an "isentropic trough" usually associated with an Occlusion, but corresponding to a rising warm conveyor belt which is superimposed upon the unstable zone. Depending on the season the layer of the warm conveyor belt can be rather deep.
• Temperature advection:
  As the Thickness Ridge Cloudiness appears in front of a Cold Front, it generally exists within positive temperature advection (WA) at all levels This is, in effect, the dominating warm conveyor belt stream.
• Relative humidity:
  Although there is a maximum of humidity at the low levels, the rising air of the warm conveyor belt stream leads to a secondary relative humidity maximum associated with Thickness Ridge Cloudiness in middle and upper levels.
• Divergence:
  Although there is a distinct convergence maximum in lower levels, there is a broad zone of convergence representing the warm conveyor belt stream at middle and higher levels.
• Vertical motion (Omega):
  Convergence in lower levels leads to a distinct maximum of upward motion in middle and even higher levels.

Isentropes, equivalent potential temperature

The above left diagram shows a typical appearance of isentropes associated with a Thickness Ridge Cloudiness in summer time. The tongue of warm air represented by a maximum, or at least a bulge of isentropes within the centre of a vertical cross section, is a most evident feature with Thickness Ridge Cloudiness. The above right diagram shows the common distribution of isentropes for the winter season, where the warm air tongue is not so strong. The cross section below shows a typical distribution of isentropes in the summer season.

Temperature advection

In the above riht hand cross section, distinct WA, representing the rising warm conveyor belt, can clearly be seen in the central and right side parts. The maximum located at the right side at lower levels can be assigned to the Warm Front (indicated by ascending tight gradient of isentropes) whereas the secondary maximum near the centre at middle levels and the maximum at upper levels can clearly be linked to the Thickness Ridge Cloudiness.

Relative humidity

A broad zone of increased relative humidity advected within the warm conveyor belt stream can be seen in the above right cross section.

Divergence

Vertical motion (Omega)