Figure 14a. 20101028, 12:30 UTC, Meteosat-9, IR10.8-BT (190K-230K), Angola. Example of storm with a cold ring and distinct overshooting top near the center of the storm.
Figure 14b. 20101030, 15:45 UTC, Meteosat-9, IR10.8-BT (190-230K), Angola. Another example of a storm with cold ring. In this case the cloud top (including the cold ring) is much colder as compared to the previous case; the ring is slightly warmer at its southern part. Also here an overshooting top can be seen exactly in the center of the embedded warm area.
Figure 14c. 20101122, 15:00 UTC, METEOSAT-9, IR10.8-BT (190K-230K), Democratic Republic of the Congo. An example of somewhat less regular cold ring, with two overshooting tops in the center of the ring.
Figure 14d. 20101129, 17:45 UTC, Meteosat-9, IR10.8-BT (190K-230K), Zambia and Democratic Republic of the Congo. A case documenting transition from cold ring to cold-U/V feature. Initially the storm formed a cold ring, which later warmed-up at its northern part (by "masking" part of the cold ring by higher, warmer cirrus plume, extending from center of the storm northward), resulting in cold-U appearance of the storm later on.
Figure 14e. 20080116, 17:45 UTC, Meteosat-9, IR10.8-BT (184K-224K), Mozambique, Swaziland and South Africa. Storm exhibiting a distinct cold-U/V feature, with the warm are inside it resembling a plume, originating just south of the overshooting top (the coldest spot near the cold-U/V apex). Further comments on this case are below.
The last case (shown in the Figure 14e, and also in the loop below) is a very important one, as it nicely documents one of the possibilities of how the cold-U/V feature forms. The storm, initially consisting of several separated cells, generated during its evolution various forms of embedded warm areas - beginning with smaller spots only (13:15-14:45), which later began to grow (15:00-15:45), ultimately forming a warm area resembling a large warm plume (16:00-18:30), extending downwind of the storm core. This warm plume, which formed above the anvil top, was also observed in other SEVIRI bands (for details see the link below), partially masking the cold cloud top underneath, and gave the storm its cold-U/V like appearance. This plume masking mechanism is only one of several possible mechanisms, which can form or contribute to formation of the cold-U/V storm top features. Between 18:45 - 19:00 the storm began to weaken and dissipated shortly afterwards. More information for this case can be found in the Cold-U Shaped Convective Storm Close to Maputo study.
