Altitude determination with method 3. The features observed in the detached layer are used to determine its altitude (plus sign at the centre of the diffracted shape). The external white circle shows the position of the limb above the illuminated disc. Left panel: detection at emergence from the planet shadow of Feature 1 (F1). Middle panel: detection at emergence from the planet shadow of F2 and F3. Right panel: same features observed one hour later. The crosses (x) show the earlier measured feature positions at detection time having moved eastward with the rotation of the planet. F1, F2, and F3 are now on the cloud’s western front (images by EB processed by MD). See additional movie S4.