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Figure 3.10. Idealized illustration of dynamic horizontal perturbation pressure gradient forces
(red arrows) along the sides of an anvil dome. Air decelerates as it approaches from the right
(flows over the top as in Figure 3.8) and then accelerates again as it leaves the dome on the left.
Air with less momentum from below is brought to the storm top in the dome; air with higher
momentum approaches the dome from the right, but must be slowed down. It is the adverse
pressure gradient (i.e., in the direction opposite to the flow) that slows the air down and thus
the fluid dome acts like a solid body.
infrared (IR) brightness temperatures surrounding a relatively warm region are
often seen in infrared satellite imagery ( Figure 3.11 ). Alas, cloud-top brightness
temperature does not necessarily indicate the cloud-top temperature because the
top edge of the cloud, even if the cloud is opaque, may not be in thermal equilib-
rium with its environment. Spaceborne radar and lidar observations have been
used to correlate IR signatures with penetrating tops. It has been found that pene-
Figure 3.11. Color-enhanced infrared signatures at anvil top. (Left) Cold rings in two
convective storms over central Europe as detected by METEOSAT-8. (Right) Cold UV
signature in a convective storm over Germany on May 26, 2007, as depicted by
METEOSAT-9 (from Martin Setvak).
 
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