An atmospheric wave
Each spring, a spectacular meteorological event unfolds in the skies over Australia's Gulf of Carpentaria. Known as the Morning Glory, it consists of one or more tube-like roll clouds that can stretch up to 1,000 kilometers long. These formations, a type of arcus cloud, typically measure one to two kilometers in height, with bases often just 100 to 200 meters above the ground. They advance across the sky at speeds up to 60 kilometers per hour, creating a visual display that appears like enormous waves rolling through the atmosphere.
The cloud itself is a visible sign of an atmospheric solitary wave, or soliton—a self-sustaining wave that maintains its shape as it travels. As the wave moves, moist air at its leading edge is lifted, cooling and condensing to form the cloud. At the trailing edge, the air descends, warms, and the cloud evaporates. This constant process of formation and dissipation gives the cloud its characteristic rolling motion. The passage of a Morning Glory is often marked on the ground by a sudden wind squall, a sharp jump in atmospheric pressure, and intense low-level wind shear. Sometimes up to ten distinct roll clouds can appear in parallel succession.
A precise trigger
The reliable appearance of the Morning Glory clouds in this specific region is a result of a combination of geographical and atmospheric conditions. The primary trigger involves the collision of two different sea breezes over the Cape York Peninsula, the landmass to the east of the Gulf. During the day, a sea breeze from the Coral Sea on the east coast pushes westward, while another breeze moves east from the Gulf of Carpentaria. These two air masses meet over the spine of the peninsula in the late afternoon, forcing moist air upward and often forming a line of clouds.
As night falls, the air over the land cools and descends. This cooler, denser air then begins to slide westward toward the Gulf, often moving underneath a nocturnal temperature inversion—a stable layer of air where temperature increases with altitude. This interaction generates a large atmospheric wave, or undular bore, that propagates westward across the Gulf. When there is sufficient moisture in the lower atmosphere, this wave becomes visible as the Morning Glory cloud just after sunrise. The phenomenon is most frequently and predictably observed from late September to early November.
Surfing the sky
The clouds are a scientific curiosity, they also present a unique challenge and opportunity for aviators. Glider and hang-glider pilots travel from around the world to "surf" the Morning Glory. The strong vertical uplift at the front of the cloud—sometimes described as the world's biggest wave—provides enough lift for pilots to soar for hundreds of kilometers along the cloud's face. The air behind the cloud, however, is turbulent and sinking, making the activity a pursuit for experienced pilots only.
The town of Burketown in Queensland is the center for viewing and flying the Morning Glory. While the clouds have been observed sporadically in other parts of the world, the Gulf of Carpentaria is the only place where their appearance is regular and predictable. Local Indigenous people, the Gangalidda and Garawa, have known of the phenomenon for generations, calling it "Mabuntha" or "kangólgi".