Flying over the Philippine Sea, an astronaut looked toward the horizon from the International Space Station and shot this photograph of three-dimensional clouds, the thin blue envelope of the atmosphere, and the blackness of space.The late afternoon sun brightens a broad swath of the sea surface on the right side of the image. In the distance towards the horizon, a region-wide layer of clouds mostly obscures islands in the northern Philippines (at image top right). Looking toward the sun to capture an image is a special technique used by astronauts to accentuate the three dimensions of landscapes and cloudscapes due to shadows cast by these features. Two large thunderclouds rise next to one another (at image lower right). These have long tails, also known as anvils from their shape, that stretch nearly 100 km to the south. Anvils form when thunderstorm clouds rise high into the atmosphere and reach a “capping layer,” often thousands of meters (tens of thousands of feet) above sea level. Capping layers stop the upward growth of a cloud, deflecting air currents horizontally to form anvils.