Fluctuating vertical shears of wind speed have been measured using an array of towers. The statistical distributions of these shears are compared with formulas proposed by Fichtl (1971, 1972) and good agreement is found. A comparison of Fichtl's formula for the standard deviation of the fluctuating shears with a more empirical one proposed by Ramsdell (1978) shows that the latter is consistent with the former under the proper conditions. The probability of occurrence of extreme shears in speed is discussed. Directional shears are not treated. Fluctuating shears two or more times larger than the mean values are shown to be readily obtainable, and their likelihood increases as the mean measuring height increases if .delta.Z is held fixed.