Arcus clouds are dramatic, low-level horizontal formations that appear along the leading edges of thunderstorms or gust fronts. They occur in two principal forms: shelf clouds and roll clouds.
Asperatus clouds, also known as Undulatus Asperatus, are one of the most visually dramatic and recently recognised cloud formations. Their bases resemble a dark, rolling ocean seen from beneath, giving the sky a sense of movement and texture.
Pileus clouds, often called cap clouds, form as thin, smooth layers over the tops of rapidly growing cumulus or cumulonimbus towers. They signify vigorous updrafts and rapid vertical development in convective systems.
Volutus clouds, commonly known as roll clouds, are a type of Arcus Cloud. They are rare, low-level cloud formations characterized by their distinctive tube-like shape and horizontal orientation. They typically appear detached from other cloud systems and exhibit a rolling motion along a horizontal axis.
Mammatus clouds are pouch-like protrusions hanging beneath the anvil of cumulonimbus clouds or, more rarely, other cloud types. They mark areas of intense downdraft and are striking indicators of turbulent atmospheric processes.
Lenticular clouds are smooth, lens-shaped formations that develop when stable, moist air flows over mountain ranges or obstacles. They are classified within the altocumulus or cirrocumulus genera
Undulatus clouds are a recognised cloud variety characterised by wave-like patterns across the sky. The term undulatus is Latin for “wavy,” reflecting the repeating bands or ripples these clouds display. They are observed within multiple cloud genera, including Altocumulus, Stratocumulus, and Cirrocumulus.
Fallstreak or hole-punch clouds are circular or elliptical gaps in mid-level cloud layers caused by aircraft penetration through supercooled cloud decks.
Murus clouds, commonly referred to as wall clouds, are dramatic, vertically oriented cloud features that form beneath the base of a severe thunderstorm, usually a supercell cumulonimbus cloud. They are characterised by a concentrated, lowering base that can rotate and serve as a precursor to tornado formation.
Noctilucent clouds, also called night-shining clouds, are the highest clouds in the Earth’s atmosphere, forming in the mesosphere at altitudes of approximately 76 to 85 kilometres. They are primarily composed of ice crystals.
Fractus clouds are small, irregular fragments that break away from larger cloud masses. They often form beneath precipitating clouds or along gust fronts, moving rapidly and constantly changing shape.