Front intensification by jet crossing: FI by Jet
Development of thicker and mostly more convective cloud within a frontal cloud band in the left exit region of a jet streak during frontal crossing.
If a jet streak approaches and crosses a frontal zone at a large acute angle, horizontal and vertical increase of frontal cloudiness in the left exit region of this crossing jet streak can be observed. These cloud phenomena are produced by the interaction between front and jet streak. The intensification of cloudiness within the left exit region is caused by the following processes: the frontal circulation (for instance an Ana Cold Front) causes lifting processes within the front; the cross circulation in the left exit region of a jet streak causes an intensification of the temperature gradient (frontogenesis); a PVA maximum in the left exit region contributes to upward motion.