[{"data":1,"prerenderedAt":348},["ShallowReactive",2],{"learn-\u002Flearn\u002Fcloud-types-explained":3,"learn-nav-\u002Flearn\u002Fcloud-types-explained":324},{"id":4,"title":5,"body":6,"date":265,"description":266,"draft":267,"extension":268,"faqs":269,"howTo":279,"keyTakeaways":280,"meta":285,"navigation":286,"path":287,"quiz":288,"seo":314,"series":279,"seriesOrder":279,"sources":315,"stem":321,"topic":322,"__hash__":323},"learn\u002Flearn\u002Fcloud-types-explained.md","Cloud types and what they tell a pilot",{"type":7,"value":8,"toc":255},"minimark",[9,13,19,24,40,84,87,91,106,126,136,140,143,164,172,176,183,205,209,235,239],[10,11,12],"p",{},"A glance at the sky is a weather briefing in itself, if you can read it. The clouds overhead are the visible result of what the air is doing, and the same naming scheme used by every meteorologist tells you whether the air is stable or unstable, wet or drying, and whether the weather ahead is settling or building.",[14,15,16],"blockquote",{},[10,17,18],{},"This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.",[20,21,23],"h2",{"id":22},"the-ten-genera-and-the-naming-scheme","The ten genera and the naming scheme",[10,25,26,27,34,35,39],{},"The ",[28,29,33],"a",{"href":30,"rel":31},"https:\u002F\u002Fcloudatlas.wmo.int\u002Fen\u002Fhome.html",[32],"nofollow","WMO International Cloud Atlas"," classifies clouds into ",[36,37,38],"strong",{},"ten basic types, called genera",", grouped by the height of their base. The names are built from a handful of Latin roots that, once learned, decode themselves:",[41,42,43,54,60,69,75],"ul",{},[44,45,46,49,50,53],"li",{},[36,47,48],{},"cirro"," or ",[36,51,52],{},"cirrus",": high and wispy, made of ice crystals;",[44,55,56,59],{},[36,57,58],{},"alto",": middle level;",[44,61,62,49,65,68],{},[36,63,64],{},"stratus",[36,66,67],{},"strato",": a flat, layered sheet;",[44,70,71,74],{},[36,72,73],{},"cumulus",": a heaped, lumpy cloud;",[44,76,77,49,80,83],{},[36,78,79],{},"nimbus",[36,81,82],{},"nimbo",": rain-bearing.",[10,85,86],{},"So altostratus is a middle-level layer, cumulonimbus is a heaped rain cloud, and nimbostratus is a layered rain cloud.",[20,88,90],{"id":89},"high-middle-and-low","High, middle and low",[10,92,93,94,99,100,105],{},"The base-height bands overlap and shift with latitude and season, so the ",[28,95,98],{"href":96,"rel":97},"https:\u002F\u002Fwww.metoffice.gov.uk\u002Fweather\u002Flearn-about\u002Fweather\u002Ftypes-of-weather\u002Fclouds",[32],"UK Met Office"," and the ",[28,101,104],{"href":102,"rel":103},"https:\u002F\u002Fwww.faa.gov\u002Fregulationspolicies\u002Fhandbooksmanuals\u002Faviation\u002Ffaa-h-8083-28b-aviation-weather-handbook",[32],"FAA Aviation Weather Handbook"," give them as typical temperate-latitude figures rather than hard limits:",[41,107,108,114,120],{},[44,109,110,113],{},[36,111,112],{},"High"," (bases roughly above 20,000 feet): cirrus, cirrocumulus, cirrostratus, all ice-crystal cloud.",[44,115,116,119],{},[36,117,118],{},"Middle"," (bases roughly 6500 to 20,000 feet): altocumulus, altostratus, and nimbostratus, the thick grey rain layer.",[44,121,122,125],{},[36,123,124],{},"Low"," (bases roughly below 6500 feet): stratus, stratocumulus, and the bases of cumulus and cumulonimbus.",[10,127,128,129,131,132,135],{},"Two of these, ",[36,130,73],{}," and ",[36,133,134],{},"cumulonimbus",", have large vertical extent and can tower through all three layers from a low base to a high top.",[20,137,139],{"id":138},"the-one-distinction-that-matters-most","The one distinction that matters most",[10,141,142],{},"For a pilot the most useful split is not the height band but the shape, because the shape reveals what the air is doing:",[41,144,145,155],{},[44,146,147,150,151,154],{},[36,148,149],{},"Cumuliform (heaped) cloud"," forms in ",[36,152,153],{},"unstable air"," rising in convective currents. It brings showers, gusty winds, turbulence and good visibility between the showers.",[44,156,157,150,160,163],{},[36,158,159],{},"Stratiform (layered) cloud",[36,161,162],{},"stable air"," lifted gently over a wide area. It brings steady, widespread cloud, often continuous rain or drizzle, and a smoother ride.",[10,165,166,167,171],{},"This ties straight back to ",[28,168,170],{"href":169},"\u002Flearn\u002Ftemperature-inversions-and-stable-air","stability and inversions",": heaps mean instability, layers mean stability.",[20,173,175],{"id":174},"a-worked-example","A worked example",[10,177,178,179,182],{},"You walk out for an afternoon flight and see, high up, thin wisps of cirrus thickening into a milky cirrostratus sheet, with altostratus greying the middle level behind it. To the west, the sky is lowering. That sequence, high ice cloud thickening and lowering into middle-level layers, is the classic signature of an ",[36,180,181],{},"approaching warm front",": stratiform cloud, gentle lift, and steady rain on the way rather than showers.",[10,184,185,186,189,190,192,193,197,198,204],{},"Contrast a summer morning where the sky starts clear, fair-weather cumulus pop up by late morning, and by early afternoon one cell has grown into ",[36,187,188],{},"towering cumulus"," with a hard, cauliflower top. That is unstable air and active convection, and if the top glaciates into an anvil it has become ",[36,191,134],{},", the thunderstorm cloud the ",[28,194,196],{"href":102,"rel":195},[32],"FAA handbook"," warns carries severe turbulence, icing, hail, lightning, downbursts and ",[28,199,203],{"href":200,"className":201},"\u002Flearn\u002Fglossary#gt-wind-shear",[202],"glossary-link","wind shear",". That one you route well around.",[20,206,208],{"id":207},"common-pitfalls","Common pitfalls",[41,210,211,217,223],{},[44,212,213,216],{},[36,214,215],{},"Height bands are typical, not fixed."," The base figures shift with latitude and season, so use them as a guide, not a measurement.",[44,218,219,222],{},[36,220,221],{},"A growing cumulus is a warning."," Towering cumulus is the stage immediately before cumulonimbus; treat rapid vertical growth as a reason to stay clear.",[44,224,225,228,229,234],{},[36,226,227],{},"In reports, cloud base is above the aerodrome."," The cloud heights in a ",[28,230,233],{"href":231,"className":232},"\u002Flearn\u002Fglossary#gt-metar",[202],"METAR"," are heights above the field, not above sea level.",[20,236,238],{"id":237},"in-pilot-efb","In Pilot EFB",[10,240,241,242,131,245,249,250,254],{},"Pilot EFB decodes the cloud groups in the ",[28,243,233],{"href":244},"\u002Flearn\u002Fhow-to-read-a-metar",[28,246,248],{"href":247},"\u002Flearn\u002Fhow-to-read-a-taf","TAF",", so the amounts and bases are in plain language alongside the raw report, and it keeps the ",[28,251,253],{"href":252},"\u002Flearn\u002Fthunderstorms-and-convective-weather","thunderstorm and convective"," warnings you have pulled in one place. A briefing you have already pulled stays readable with no signal; fetching a fresh observation needs a connection. Pilot EFB is not a certified Electronic Flight Bag, so treat it as a study and planning aid and brief from your official source of record.",{"title":256,"searchDepth":257,"depth":257,"links":258},"",2,[259,260,261,262,263,264],{"id":22,"depth":257,"text":23},{"id":89,"depth":257,"text":90},{"id":138,"depth":257,"text":139},{"id":174,"depth":257,"text":175},{"id":207,"depth":257,"text":208},{"id":237,"depth":257,"text":238},"2026-06-22","The ten cloud genera grouped into high, middle and low, the difference between heaped and layered cloud, and how to read what each type is telling you about stability, moisture and the weather ahead.",false,"md",[270,273,276],{"q":271,"a":272},"How are clouds classified?","The World Meteorological Organization classifies clouds into ten basic types called genera, grouped by the height of their base into high, middle and low levels, plus clouds of large vertical extent. The names combine Latin roots: cirro or cirrus for high and wispy, alto for middle, stratus for layered, cumulus for heaped, and nimbus for rain-bearing.",{"q":274,"a":275},"What is the difference between cumuliform and stratiform cloud?","Cumuliform (heaped) clouds like cumulus and cumulonimbus form in unstable air that is rising in convective currents, and they bring showers, gusty winds and turbulence. Stratiform (layered) clouds like stratus and altostratus form in stable air that is being lifted gently over a wide area, and they bring steady, widespread cloud and often continuous rain or drizzle with a smoother ride.",{"q":277,"a":278},"Which cloud is the one to avoid?","Cumulonimbus, the thunderstorm cloud. It is a towering convective cloud of huge vertical extent, often with an anvil top, and it carries severe turbulence, icing, hail, lightning, downbursts and wind shear. Towering cumulus is the stage just before it. Both are coded separately in aviation reports for a reason and should be given a wide berth.",null,[281,282,283,284],"Clouds are classified into ten genera grouped by base height into high, middle and low, plus clouds of large vertical extent.","The names tell you the type: cirro and cirrus for high ice cloud, alto for middle, stratus for layered, cumulus for heaped, nimbus for rain-bearing.","Heaped cumuliform cloud means unstable, rising air with showers and turbulence; layered stratiform cloud means stable air with steady, widespread weather.","Cumulonimbus is the hazard cloud, carrying severe turbulence, icing, hail, lightning and shear, and is given a wide berth.",{},true,"\u002Flearn\u002Fcloud-types-explained",[289,298,306],{"q":290,"options":291,"answer":296,"explanation":297},"Which prefix or root tells you a cloud is at the high level?",[292,293,294,295],"Alto","Cirro or cirrus","Strato","Nimbo",1,"Cirro or cirrus marks high cloud, made of ice crystals; alto marks middle cloud, and stratus or strato marks layered cloud.",{"q":299,"options":300,"answer":296,"explanation":305},"Heaped cumuliform clouds tell you the air is doing what?",[301,302,303,304],"Sinking in stable layers","Rising in unstable, convective currents","Completely still","Flowing only horizontally","Cumuliform clouds form in unstable air rising in convective currents, which is why they bring showers, gusts and turbulence, unlike the gentle lift behind layered stratiform cloud.",{"q":307,"options":308,"answer":257,"explanation":313},"Which cloud carries severe turbulence, hail, lightning and wind shear?",[309,310,311,312],"Cirrus","Stratocumulus","Cumulonimbus","Altostratus","Cumulonimbus is the thunderstorm cloud, a towering convective cloud with severe turbulence, icing, hail, lightning, downbursts and shear, and it should be given a wide berth.",{"title":5,"description":266},[316,317,319],{"label":33,"url":30},{"label":318,"url":102},"FAA Aviation Weather Handbook (FAA-H-8083-28B)",{"label":320,"url":96},"UK Met Office: Cloud types","learn\u002Fcloud-types-explained","Weather","TiCkWEvLPsuuV3xQ7Vy4ro5SBm1w7ykT1957k_jauyQ",{"related":325,"newer":341,"older":326,"series":279},[326,331,335],{"path":327,"title":328,"description":329,"date":265,"topic":322,"draft":267,"minutes":330,"series":279,"seriesOrder":279},"\u002Flearn\u002Fjet-stream-and-clear-air-turbulence","The jet stream and clear-air turbulence","What a jet stream is, where it sits near the tropopause, and why the wind shear around it produces clear-air turbulence that arrives with no cloud to warn you.",4,{"path":332,"title":333,"description":334,"date":265,"topic":322,"draft":267,"minutes":330,"series":279,"seriesOrder":279},"\u002Flearn\u002Fmountain-waves-and-rotor","Mountain waves and rotor","How stable air flowing over high ground sets up standing mountain waves and the violent rotor beneath them, the cloud signs that give them away, and why the turbulence and downdraughts deserve respect.",{"path":336,"title":337,"description":338,"date":265,"topic":322,"draft":267,"minutes":330,"series":339,"seriesOrder":340},"\u002Flearn\u002Ftaf-change-groups","TAF change groups: TEMPO, BECMG, PROB and FM","A deeper look at the change groups that make a TAF a forecast rather than a snapshot, with the exact meaning of FM, BECMG, TEMPO and PROB and a worked example that decodes them in order.","decode-the-weather",6,{"path":342,"title":343,"description":344,"date":265,"topic":345,"draft":267,"minutes":330,"series":346,"seriesOrder":347},"\u002Flearn\u002Fairspace-speed-limits","The 250-knot speed limit and other airspace speed rules","Why there is a 250-knot speed limit below 10,000 feet, the slower 200-knot limits near and under busy airspace, and how the FAA and EASA wordings line up and differ, with a worked descent that puts the rules in order.","Operations","plan-a-vfr-cross-country",7,1782089963504]