English: The South Sandwich Islands conspired with air currents to make wave patterns in clouds. Saunders, Montagu, and Bristol Islands, part of the South Sandwich chain, all trigger V-shaped waves that fan out toward the east. The white clouds over the dark ocean water vaguely resemble zebra stripes. The South Sandwich Islands are of volcanic origin—Bristol and Montagu have been active during recorded history—and all the islands poke rugged summits above the ocean surface. The islands disturb the smooth flow of air, creating waves that ripple through the atmosphere downwind of the obstacles.