Atmosphere-skimming showers are initiated by cosmic rays with an incoming direction such that the full development of the cascade occurs inside the atmosphere without reaching the ground. This new class of showers has been observed in balloon-borne experiments such as ANITA, but a characterisation of their properties is lacking. In this article, we have performed simulations of atmospheric-skimming showers using the latest version of the ZHAireS-RASPASS shower simulation program. We have determined the properties of the longitudinal profile of the shower and its fluctuations as a function of cosmic-ray energy, direction and primary mass. We have studied the phase-space of cosmic-ray arrival directions where detection in balloon-borne experiments is more likely, and have found that only in a small range of directions, the showers are sufficiently developed before reaching the altitude of the detector. The interplay between the Earth’s magnetic field, the long distances over which atmosphere-skimming showers develop, and the low density of the atmosphere they traverse gives rise to several effects that are not seen in
downward-going cascades. Our results are relevant for the design of balloon-borne experiments and the interpretation of the data they collect.