Wave clouds, thunderclouds

May 17, 1999 18:18 UTC

South of France. At the bottom right is the Mediterranean sea. A low over Spain generates a strong south to southeast wind over the Cévennes (1), which gives rise to wave clouds. These are visible at the same time on the visible and infrared images, in the shape of two slightly divergent strips (2). On the left of the images, thunderstorm clouds are visible: cumulonimbus (3). Very white spots on the infrared image, because their top, very high, is very cold. These clouds which extend largely vertically have significant shade (4) that can be seen very well on the visible image in the oblique evening light.