Investigates use of an array of spires, located at the entrance to the working section of a conventional wind tunnel, as a means of generating thick shear layers with properties similar to those of the neutrally-stable atmospheric wind. Compares data obtained in the shear layers created by sucharrays of spires with some available atmospheric data. Modifications to thespire design and a range of spire sizes have been tested and the resulting shear layer properties compared.