Cloud PointField Guide

Middle cloud

The layer where shear, waves and lenses show themselves.

Middle — 2,000 to 6,000 m18

Corona — Coloured rings hugging the sun or moonCoronaVIIThin cloud crossing the sun or moon; little weather significance on its ownAsperitas — The newest, most ominous wavy undersideAsperitasXUnsettled, turbulent air, but usually disperses without a stormAltostratus — The featureless grey veil that dims the sunAltostratusXVIRain or snow likely within 12-24 hoursBanner cloud — The flag streaming off a sharp peakBanner cloudXVIIIStrong wind streaming over a sharp peak, otherwise clearKelvin-Helmholtz — Breaking ocean waves, frozen in the skyKelvin-HelmholtzXIXStrong wind shear aloft; little direct weather significanceGlory — Rainbow rings around your own shadowGloryXXThin cloud or fog below you with the sun behind; no weather significanceVirga — Rain that falls but never landsVirgaXXIIDry air below the cloud - rain is evaporating before it can landLenticular — The 'flying saucer' of the skyLenticularXXVStrong, moist winds crossing high ground; turbulence likely aloftHorseshoe Vortex — A horseshoe that vanishes in minutesHorseshoe VortexXXIXDaytime thermals with wind shear; fair but breezyFallstreak Hole — The hole-punch cloud that sparks UFO reportsFallstreak HoleXXXThin supercooled cloud, often near flight paths; no significant weatherCloud Iridescence — Pastel rainbow colours in thin cloudCloud IridescenceXXXIIIThin cloud near the sun; no weather significanceCastellanus — Turrets that warn of afternoon thunderstormsCastellanusXXXVMid-level instability; afternoon thunderstorms may followAltocumulus — Mid-level cloudlets in patches and wavesAltocumulusXXXVIGenerally fair; morning altocumulus on humid days may signal afternoon thunderstormsNimbostratus — The thick, sunless rain- and snow-makerNimbostratusXLIProlonged precipitation, overcast conditions for extended periodsUndulatus — Ripples revealing waves in the air itselfUndulatusXLIIIWind shear between air layers; little direct weather significancePileus — The fleeting 'halo cap' on a rising towerPileusXLVIIVigorous rising convection; a thunderstorm may be developingVelum — The thin veil draped through a storm towerVelumLMoist, stable air pierced by storm towers; convection buildingLacunosus — A honeycomb of cloud holesLacunosusLIPockets of sinking air in thin cloud; no weather significance