A Texas couple have filmed a magnificent roll cloud in Timbercreek Canyon, south of Amarillo. The “sideways tornado” looks intimidating, and there can be intense wind-shear accompanying it, but damage on the ground is relatively rare.

Roll clouds are a category of low horizontal clouds known as acrus clouds. The turn up now and then around the world, and occasionally get filmed, but in most places you have to be very lucky to see one, even near coastlines where they are a little more common.

However, in the Gulf of Carpentaria, northern Australia, roll clouds up to 1000km long usually happen 2-3 times a week through October, often with several of lined up behind each other. The chance to glide on these so called “Morning Glories” has become a tourist attraction to the remote area, as well as drawing scientific study.

^{Mick Petroff. Roll Clouds or Morning Glories lined up over the Gulf of Carpentaria}

Roll clouds are a form of soliton, a self-reinforcing solitary wave that keeps its shape as it travels, although it can gain or lose amplitude. Their physics is important for fields such as fiber optics. Other examples include many tidal bores and rogue waves.

H/T Livescience