Apollonaris Patera in Color IR (Released 2 August 2004)

On this image you can see two infrared frames of the same area on Mars.One of the images (in black and white) represents a single wavelength or band of the THEMIS IR instrument, while the other image (in false color) represents 3 different bands. The image with the various colors was created with a technique called Decorrelation Stretch (DCS). In this technique individual bands of the THEMIS IR instrument are stretched to better show compositional variations throughout the whole range. After the bands are stretched they are overlayed on one another and colors are assigned to each band. This makes up the colors in the image.The cyan color present on the southwest flank of the volcano Apollonaris Patera is due to the presence of water ice clouds. Much like Earth, Mars has orographic cloud formations. Similar to cloud formations in the mountains in the summer on Earth (though without the associated thunder and rain, of course) water ice clouds form near volcanoes and other topographic features on Mars. Because THEMIS does not have stereo-vision it is impossible to tell the height of the clouds from the image and the color signature appears as if it was on the surface.