High level clouds have their cloud bases above 6km (20,000ft). They include three genera (click thumbnails for more information): -

	Cirrus (Ci) – white wispy clouds composed of ice crystals
	Cirrostratus (Cs) – high, white milky cloud, sometimes forming a halo around the sun or moon
	Cirrocumulus (Cc) – the famous “mackerel sky” is one of several forms of these interesting, and less common, clouds