AbstractRefractive index, temperature and wind profiles, to a height of 2,100 m, obtained from a tethered balloon flight are analysed in terms of static and dynamic stability on a day of an elevated temperature inversion associated with stable layering in humidity and strong intermittent temperature fluctuations. It is shown that large humidity gradients in stratified layers contribute significantly to the total density gradient and must be taken into account in the evaluation of Richardson number. Fluctuations in temperature and humidity occurred both in regions of strong positive and negative static stability. No evidence was found to suggest that the occurrence of fluctuations is associated with a critical gradient Richardson number. Cross‐correlation between humidity and temperature was found to be strongly negative across the boundaries of stratified layers and positive in strong intermittent bursts of temperature observed at the top of the temperature inversion. Spectral slopes of refractive index, temperature and humidity in the region of strong density gradients were found to be, in general, greater than the ‐5/3 slope predicted by inertial subrange the