Experimental data on the energy spectra, correlation coefficients and energy isotropy of atmospheric turbulence at low elevations are presented. It is shown that the very simple formulas derived with the aid of Kolmogoroff's Similarity Hypothesis are remarkably consistent with the experimental evidence of this and other research projects. The Similarity Hypothesis, although only directly applicable to turbulent eddies small enough to be isotropic, appears in some instances to be useful in its simplest form for atmospheric problems with scales varying between one cm and a thousand km. Some possible applications are described together with the regions where the Similarity Hypothesis might be expected to hold. Several measurements of vertical turbulent heat flux at various elevations were made with rapid-response equipment. A systematic variation of the heat flux with elevation was noted even at the low elevations involved.