The conceptual model Cold Front in Cold Advection is a subtype of the complete group of Cold Fronts. In contrast to classical Cold Fronts, Cold Front (CF) in Cold Advection (CA) is characterised by the following main features: the zero line of temperature advection is not within the frontal cloud band, but clearly in advance which means that the whole cloud band is under the influence of CA.

In general, the appearance of a CF in CA in the satellite image is very similar to a classical Cold Front with multi-layered cloudiness, so the identification is more easily done using key parameters. For the appearance in satellite imagery compare the conceptual model Cold Front (see Cold Front - Cloud structure in satellite image ).

Sometimes it is possible to recognize a Cold Front in Cold Advection from the satellite image because in about a quarter of the cases only low cloudiness is found. These types are represented by a white cloud band in VIS and a grey cloud band in IR images (see Key parameters).

The main feature in the WV image is the very dark stripe along the rear edge of the cloud band representing dry air which is characeristic for all CFs in CA.

The example from 30 January 1999/06 UTC shows a CF in CA in the eastern Mediterranean which clearly has lower (warmer) cloud tops than those of the Occlusion and the Warm Front Bands to in the north. The WV image is very dark in the cloud band area and black at the rear edge. The example from 25 January 1999/06 UTC shows a typical case where only one part of the complete Cold Front lies within cold advection. It differs from the rest of the frontal cloud band by its fractured structure. More to the southwest the front becomes a classical Cold Front, i.e. the zero line of temperature advection approaches the cloud band. In the IR image the CF in CA part seems to consist of somewhat lower (warmer) cloud tops although the difference is not as distinct as in the first case described.

Development in connection with classical Cold Fronts

The development of a Cold Front in Cold Advection is very often associated with a classical polar front and appears during the later stages when temperature contrasts diminish or cold air overruns the system.

The sequence of four satellite images below shows the following development: In the beginning the zero line of TA can be found within the frontal cloud band; CA is approaching from the rear side a zone of WA which accompanies the leading part of the cloud band. During the development this WA area becomes more and more broken and can be regarded as the effect of progressing cold air. In the end the whole cloud band is within CA.

Development within cold air

In contrast to the previously mentioned cases where a classical polar front development has taken place another frequent reason for the development of a Cold Front in Cold Advection is a cold air development process (see Cold Air Development ), which describes the increase in size of a Comma feature to frontal scale and, in the process, gaining some frontal characteristics. Such a development takes place at the rear of classical Cold Fronts and an interaction of both systems at a later stage is probable. The area of interest is Corsica and Sardinia where cloud features appear as a Comma in its development stage; three hours later a distinct intensification of cloudiness as well as a spiral structure can be observed immediately east of Corsica and Sardinia. Again, three hours later a dramatic intensification of cloudiness in the Comma tail region has produced a huge Comma typical of a later stage of cold air development.

6 hours later the former CAD has developed to a CF in CA extending from S. Italy to N. Africa. Cloudiness has become lower over the Mediterranean Sea (a change from white to grey).

In the corresponding WV image, the CF in CA is characterised by a grey band with some white stripes in it. The rear edge shows a sharp gradient to a black (very dry) area.

Development by merging of two synoptic systems

Sometimes the evolution is reversed. Two frontal systems are merging and then the rear front (having previously been a classical Cold Front) becomes a Cold Front in Cold Advection. The frequency of occurrence of the different developments described above is about the same.