Figure 6-15 Volcanoes on Venus and Mars (a) The false color in this computer-generated perspective view suggests the actual color of sunlight that penetrates Venus’s thick clouds. The brighter color of the extensive lava flows indicates that they reflect radio waves more strongly. To emphasize the gently sloping volcanoes, the vertical scale has been exaggerated 10 times. (b) These volcanoes of Mars, more than 9 mi (15 km) high, also have gently sloping sides and bluish clouds often appear in the afternoons, topping the summits of the volcanoes. These clouds, made of water ice crystals, form on most Martian afternoons as warm air containing water vapor rises up the slopes and freezes.