Three-Dimensional Structure of Convective Storms and the Role of Vertical Shear in Storm Life Cycle.

摘要

A model is presented which describes the three-dimensional location of the updraft in a convective storm as a function of the wind velocity in the low-level inflow to the storm and the storm's motion. This updraft-plane model was used to interpret doppler velocities in RHI scans. The updraft-plane model led to the following hypothesis on the role of vertical shear in the environmental wind in controlling the life cycle of convective storms. If there is an alignment between the horizontal velocity of the middle level air in which the downdraft originates and the orientation and motion of the updraft plane, then the downdraft air, as it sinks through the storm toward the ground, will continually find itself underneath the updraft such that precipitation evaporation and precipitation loading many maintain and strengthen the downdraft. Conversely, if an alignment is not present, then the downdraft may not be maintained and the convective storm may be of the short-lived type.