  The footprint of radio emission from extensive air showers is known to
exhibit asymmetries due to the superposition of geomagnetic and charge-excess
radiation. For inclined air showers a geometric early-late effect disturbs the
signal distribution further. Correcting CoREAS simulations for these
asymmetries reveals an additional disturbance in the signal distribution of
highly inclined showers in atmospheres with a realistic refractive index
profile. This additional apparent asymmetry in fact arises from a systematic
displacement of the radio-emission footprint with respect to the Monte-Carlo
shower impact point on the ground. We find a displacement of $\sim
1500\,\text{m}$ in the ground plane for showers with a zenith angle of
$85^\circ$, illustrating that the effect is relevant in practical applications.
A model describing this displacement by refraction in the atmosphere based on
Snell's law yields good agreement with our observations from CoREAS
simulations. We thus conclude that the displacement is caused by refraction in
the atmosphere.
