Using data obtained from a probe mounted on the flying cable of a tethered kite balloon, this paper presents a fairly comprehensive description of the structure of a ‘hummocky’ subsidence inversion and the associated air motions, including the formation and breakdown of billows at the crests of the hummocks. Below the inversion, the transfer of warm air downwards was detected and the rate at which this occurred estimated using the model proposed by Readings et al. (1973). This estimate is shown to be in good agreement with that derived from some radio-sonde ascents. The fluxes of potential heat downwards at the inversion and upwards at the ground are estimated and their ratio is shown to be about 0.25.