Standard deviations for vertical velocity and scalar quantities, such as temperature, T, and specific humidity, q, were analyzed on the basis of Monin-Obukhov (M-O) similarity theory in the atmospheric surface layer. The correlation coefficient between scaler quantities T and q, \RTq\, was derived from the similarity functions and can be expressed as the ratio of B-T/B-q (B-T less than or equal to B-q), where parameter B is the value of the normalized standard deviation of any scalar quantity at neutral conditions.