All entries
Every entry in the guide, in the order it runs through the year — one cloud, optic or feature a week.
In order through the yearNo.
Low cloud — genusThe classic fair-weather puffballCumulusI
Supplementary featureThe sky's hanging pouchesMammatusII
Optical phenomenon — ice crystalsThe bright ring around sun or moon22° HaloIII
Special cloud (upper atmosphere)Earth's highest, glowing-at-night cloudsNoctilucentIV
Special cloud — roll cloud (volutus)A 1,000 km tube of cloud glider pilots surfMorning GloryV
High cloud — genusDelicate ice-crystal brushstrokesCirrusVI
Optical phenomenon — diffractionColoured rings hugging the sun or moonCoronaVII
Special cloud — fire cloud (flammagenitus)The cloud a wildfire builds above itselfPyrocumulusVIII
Surface-level stratusCloud at ground levelFogIX
Supplementary featureThe newest, most ominous wavy undersideAsperitasX
Low cloud — genusThe world's most common cloud, in lumpy rollsStratocumulusXI
Optical phenomenon — refractionSunlight unravelled by falling raindropsRainbowXII
Special cloud — polar stratospheric'Mother-of-pearl' clouds glowing in winter twilightNacreousXIII
Supplementary feature (arcus)The menacing wedge on a storm's leading edgeShelf cloudXIV
Optical phenomenon — scatteringSunbeams fanning through gaps in cloudCrepuscular raysXV
Mid cloud — genusThe featureless grey veil that dims the sunAltostratusXVI
Optical phenomenon — ice crystalsTwin 'false suns' flanking the real oneSun dogsXVII
Special cloud — orographicThe flag streaming off a sharp peakBanner cloudXVIII
Supplementary feature (fluctus)Breaking ocean waves, frozen in the skyKelvin-HelmholtzXIX
Optical phenomenon — diffractionRainbow rings around your own shadowGloryXX
High cloud — genusTiny rippled grains — rarest of the high cloudsCirrocumulusXXI
Supplementary featureRain that falls but never landsVirgaXXII
Ground-level ice crystalsGlittering airborne ice that makes halos at eye levelDiamond dustXXIII
Optical phenomenon — refractionA ghostly white rainbow in fogFogbowXXIV
Special cloud (Altocumulus lenticularis)The 'flying saucer' of the skyLenticularXXV
Multi-level cloud — genusThe towering storm factoryCumulonimbusXXVI
Surface fog — evaporationWhen the sea appears to smokeSteam FogXXVII
Optical phenomenon — ice crystalsA shaft of light standing above a low sunSun PillarXXVIII
Rare cloud — transient vortexA horseshoe that vanishes in minutesHorseshoe VortexXXIX
Supplementary feature — cavumThe hole-punch cloud that sparks UFO reportsFallstreak HoleXXX
Low cloud — genusThe grey blanket that becomes fogStratusXXXI
Supplementary feature — murusThe lowered base where tornadoes are bornWall CloudXXXII
Optical phenomenon — diffractionPastel rainbow colours in thin cloudCloud IridescenceXXXIII
Special — fire-storm cloudWhen a fire grows its own thunderstormPyrocumulonimbusXXXIV
Cloud species — castellanusTurrets that warn of afternoon thunderstormsCastellanusXXXV
Mid cloud — genusMid-level cloudlets in patches and wavesAltocumulusXXXVI
Optical phenomenon — perspectiveSunbeams converging opposite the sunAnticrepuscular RaysXXXVII
Cloud variety — radiatusParallel cloud rows along the windCloud StreetsXXXVIII- Special cloud — waterfall-madeCloud born from waterfall sprayCataractagenitusXXXIX
Supplementary feature — tubaThe spinning column reaching for the groundFunnel Cloud & TornadoXL
Mid cloud — genusThe thick, sunless rain- and snow-makerNimbostratusXLI
Optical phenomenon — ice crystalsThe 'upside-down rainbow' overheadCircumzenithal ArcXLII
Cloud variety — undulatusRipples revealing waves in the air itselfUndulatusXLIII
Accessory cloud — pannusRagged shreds racing beneath a stormFractus / ScudXLIV
Optical phenomenon — refractionA rainbow made by moonlightMoonbowXLV
Special — contrail cirrusAircraft contrails spread into man-made cirrusHomomutatusXLVI
Accessory cloud — pileusThe fleeting 'halo cap' on a rising towerPileusXLVII
High cloud — genusThe thin ice veil that haloes the sunCirrostratusXLVIII
Optical phenomenon — ice crystalsVertical beams above ground lights on frozen nightsLight PillarsXLIX
Accessory cloud — velumThe thin veil draped through a storm towerVelumL
Cloud variety — lacunosusA honeycomb of cloud holesLacunosusLI
Optical phenomenon — refractionThe split-second green at the horizon at sunsetGreen FlashLII