High clouds, sea, mountains, forests
South-west of France by a heat day of June. On the infrared image, the hot ground (1) appears very dark whereas the sea (2), colder, is brighter. In bottom of the image, the Pyrenees (3) are also brighter than the plain because the ground is less hot. On the visible image, the sea (4) is darker than the land (5), because it absorbs more the solar radiation. In the same way, the Landes forest (6) appears darker than the surrounding areas. Clouds over the sea (7) are white on the infrared image. That means they are cold, and thus they are high clouds. On the visible image, these clouds are not easy to see: they are thin clouds. They are probably cirrus.