Article Type:
Research Article

On the Classification of Vertical Wind Shear as Directional Shear versus Speed Shear

Paul Markowski Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania

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Yvette Richardson Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania

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Print Publication:
01 Apr 2006
DOI:
https://doi.org/10.1175/WAF897.1
Page(s):
242–247
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Abstract

Vertical wind shear is commonly classified as “directional” or “speed” shear. In this note, these classifications are reviewed and their relevance discussed with respect to the dynamics of convective storms. In the absence of surface drag, storm morphology and evolution only depend on the shape and length of a hodograph, on which the storm-relative winds depend; that is, storm characteristics are independent of the translation and rotation of a hodograph. Therefore, traditional definitions of directional and speed shear are most relevant when applied to the storm-relative wind profile.

Corresponding author address: Dr. Paul Markowski, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802. Email: pmarkowski@psu.edu

Abstract

Vertical wind shear is commonly classified as “directional” or “speed” shear. In this note, these classifications are reviewed and their relevance discussed with respect to the dynamics of convective storms. In the absence of surface drag, storm morphology and evolution only depend on the shape and length of a hodograph, on which the storm-relative winds depend; that is, storm characteristics are independent of the translation and rotation of a hodograph. Therefore, traditional definitions of directional and speed shear are most relevant when applied to the storm-relative wind profile.

Corresponding author address: Dr. Paul Markowski, Dept. of Meteorology, The Pennsylvania State University, 503 Walker Bldg., University Park, PA 16802. Email: pmarkowski@psu.edu

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