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Cold front1/28/2024 ![]() In contrast to the Ana Cold Front, the ascending warm conveyor belt is overrun by dry air, which is transported within the relative stream of the dry intrusion. It is now generally considered that a Kata Cold Front evolves from an Ana Cold Front. Satellite images show parts of this process of cloud decay (see Cloud structure in satellite image). In this case, the main zone of cloudiness and precipitation appear in front of the surface front. While the rearward component can be explained by ageostrophic wind flow in the planetary boundary layer due to friction, the parallel or even foreward sloping warm conveyor within the middle and higher levels is in accordance with the geostrophic wind relation.Īccording to classical ideas, in this type of front the warm air follows processes similar to the Ana Cold Front, however, the ascent of air is restricted by dry descending air originating from behind the front and, consequently, dissipating the higher clouds. The sharp rear cloud edge of frontal cloudiness marks the transition between the two relative streams and is accompanied by a limiting stream line.Īs mentioned in literature, real examples of CF do not always show these model characteristics, but sometimes even show parallel or even forward inclined warm conveyor belts. Parallel to the warm conveyor belt there is a dry stream (dry intrusion). This leads to the same result mentioned above, with the frontal cloud band and precipitation appearing behind the surface front. This conveyor belt has a rearward component relative to the movement of the front. If one describes the situation using conveyor belt theory, the frontal cloud band and precipitation are related to an ascending warm conveyor belt. Only in the case where there are high upper level winds, does the high cloud extend downstream ahead of the surface front, leading to a TFP maximum within the cloud band. Satellite images confirm this structure (see Cloud structure in satellite image). Consequently, in this case the main zone of cloudiness and precipitation appear behind the surface front (indicated by the TFP). The cloud band develops, inclined rearward from the surface cold front. This convergence forces the warm, moist air to ascend on the frontal surface. Therefore within the following paragraphs these cold front types are described.Īccording to classical ideas cold air moves rapidly against warm air, thereby creating convergence at the surface line between the two airmasses. From the viewpoint of satellite meteorology, the conveyor belt model presents new ideas. Many conceptual models have been developed to depict fronts the most classical ones are the for Ana Cold Front and the Kata Cold Front.
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