ALTOCUMULUS are a medium height cloud, at a height in the range 7,000 to 16,000ft.They are a lower & rather larger version of cirrocumulus cloud.They are usually white in colour. Within this variety of clouds are some of the most spectacular-looking in the heavens e.g. flying saucer shaped, doughnut-shaped, lens shaped, ripples & waves. They often form where an airstream has crossed a high mountain area.