5.6 SHEAR: Wind Shear
Figure 61 SHEAR Example Configuration
SHEAR detects wind shear in the atmosphere, allowing the detection of microbursts, gust
fronts, mesocyclones, cold fronts, and atmospheric waves.
Wind shear is associated with many phenomena:
Microbursts
Associated with convective storms. Extremely hazardous to aircraft during landing or
takeo. Microbursts are characterized by positive values of the radial shear (strongly
divergent outflow) in a roughly circular region, typically less than 3 km (1.9 mi) in size.
Gust Fronts
Caused by cold outflow from a convective storm (perhaps a microburst) colliding with
the surrounding air. They are characterized primarily by negative values of the radial
shear (convergence). However, depending on the geometry, they can also create
positive values of the radial shear and azimuthal shear of either sign.
Mesocyclones
Characterized by rotation. Mesocyclones are associated with tornadoes. The azimuth
shear is used to detect mesocyclones.
Cold Fronts
Similar to gust fronts, but much larger in extent.
IRIS Product and Display User Guide M211319EN-H
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