Evolution of the cloud discontinuity at the nightside lower clouds. These 2.26μm images from IRTF/SpeX display the manifestation of the discontinuity at the nightside lower clouds on 2022 February 4 (a). Even though the abrupt change in the clouds’ opacity on February 15 (b) and 20 (c) suggest the reappearance of the first discontinuity after several full revolutions, their zonal speeds match those of the background wind within the error bars. The fast increase in zonal wind speeds after February 4 (see Fig. 2a) suggests a probable dissipation of the wave, while leaving a persistent artefact of its effect on the opacity of the nightside lower clouds.