by ZAMG and DHMZ

Common Remarks

Three types of cloudiness in the thickness ridge are distinguished regarding their relation to the frontal cloud band as well as to their cloud structures:

  1. "isolated" type, without any frontal cloud band to the rear;
  2. "front-disconnected" type, consisting of cloudiness in the thickness ridge which is clearly separated from the frontal cloud band;
  3. "front-connected" type, which consists of cloudiness (mainly cells) along the leading side of the frontal cloud band.

There is some overlap between the different conceptual models. The third type is often seen when there is intensive convective development under the influence of cold and dry air at upper levels, originating from the rear side of the frontal cloud band. This seems to be very similar to MCS developments described in the relevant chapter. (see Appearance in vertical cross section )
The two other types of model lie within the uniform air mass of a rising warm conveyor belt and, as such, also consist of non-convective cloudiness, although convection will occur very often, especially in summer time.
On the basis of an observed, dominating warm conveyor belt, the isolated type will be signified as "warm conveyor belt".
Consequently only the second type is regarded and diagnosed as Thickness Ridge Cloudiness.