Transition from the surface layer to the free convection layer of the unstable atmospheric boundary layer is discussed mainly from the standpoint of the budget relations of thermal variance and kinetic energy. The data used here cover a wide range of stability for unstable conditions (0.1< -z/L< 62) obtained over the Bonneville Salt Flats Utah in 1970. The dimensionless terms in the budget equations obey the Obukhov's similarity law.The thermal variance transport term changes sign from divergence to convergence around -z/L =1 as -z/L increases. This is approximately balanced by the difference between the production and the dissipation rate throughout the analyzed stability range. Dissipation rates of kinetic energy and temperature fluctuations are well related to the spectral peak wavelength.The spectral peak wavelength and the length scale determined by the dissipation and the total variances decreases with -z/L for temperature fluctuations, but increases for vertical velocity fluctuations.They approach the same constant value for large -z/L.For strong instability those terms obey the free convection similarity law. The critical height and the stability at which this law becomes valid (the height of the transition) lies in 1 < -z /L <5.

Turbulence data for the International Turbulence Comparison Experiment (ITCE) held at Conargo, N.S.W. (35" 18' S.-145"lO' E.) during October, 1976 are analysed.The standard deviation (s/2)1/2 and covariance w's' measured by a number of instruments and instrument arrays have been compared& assess their field performance and calibration accuracy. Satisfactory agreement, i.e. typically 5% for (s")~/' (except in humidity) and of the order of 20% for n, was achieved, but only after consideration of:(1) Instrumental response at high frequencies.(2) Flow distortion induced by instruments and supporting structures.(3) Spatial separation of instruments used for covariance measurements.(4) Statistical errors associated with single point measurements over a finite averaging time, and with lateral separation of two sensor arrays being compared.

No abstract

No abstract

The structure of the multiple vortices formed in small scale atmospheric vortices is studied in a laboratory experiment.