[{"data":1,"prerenderedAt":273},["ShallowReactive",2],{"learn-\u002Flearn\u002Fthe-tropopause":3,"learn-nav-\u002Flearn\u002Fthe-tropopause":249},{"id":4,"title":5,"body":6,"date":189,"description":190,"draft":191,"extension":192,"faqs":193,"howTo":203,"keyTakeaways":204,"meta":209,"navigation":210,"path":211,"quiz":212,"seo":238,"series":203,"seriesOrder":203,"sources":239,"stem":246,"topic":247,"__hash__":248},"learn\u002Flearn\u002Fthe-tropopause.md","The tropopause and where weather lives",{"type":7,"value":8,"toc":179},"minimark",[9,13,19,24,40,64,68,83,110,114,133,137,140,143,147,167,171],[10,11,12],"p",{},"Climb high enough and the weather simply runs out. The clouds stop, the air smooths, and the temperature stops falling. The ceiling you have reached is the tropopause, and knowing where it sits and what it does explains why almost everything a pilot calls \"weather\" happens below it.",[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},"what-the-tropopause-is","What the tropopause is",[10,25,26,27,31,32,35,36,39],{},"The atmosphere is layered. The lowest layer, the ",[28,29,30],"strong",{},"troposphere",", is the one we live and fly in, and through it the temperature falls steadily with height. Above it lies the ",[28,33,34],{},"stratosphere",", where that cooling stops and the temperature first holds steady and then begins to rise. The boundary between the two, the level where the steady cooling ends, is the ",[28,37,38],{},"tropopause",".",[10,41,42,43,48,49,55,56,59,60,63],{},"In the ",[44,45,47],"a",{"href":46},"\u002Flearn\u002Fthe-international-standard-atmosphere","ICAO standard atmosphere",", defined in ",[44,50,54],{"href":51,"rel":52},"https:\u002F\u002Fstore.icao.int\u002Fen\u002Fmanual-of-the-icao-standard-atmosphere-extended-to-80-kilometres-262500-feet-doc-7488",[53],"nofollow","ICAO Doc 7488",", the tropopause sits at ",[28,57,58],{},"11 kilometres, about 36,000 feet",", at a temperature of about ",[28,61,62],{},"minus 56.5 degrees Celsius",", and above it the temperature is modelled as constant up to 20 kilometres. That is a reference value, not a height you will always find it at.",[20,65,67],{"id":66},"why-its-height-varies","Why its height varies",[10,69,70,71,76,77,82],{},"The real tropopause is not a fixed shelf. As the ",[44,72,75],{"href":73,"rel":74},"https:\u002F\u002Fwww.faa.gov\u002Fregulationspolicies\u002Fhandbooksmanuals\u002Faviation\u002Ffaa-h-8083-28b-aviation-weather-handbook",[53],"FAA Aviation Weather Handbook"," and the ",[44,78,81],{"href":79,"rel":80},"https:\u002F\u002Fwww.metoffice.gov.uk\u002Fweather\u002Flearn-about\u002Fweather\u002Fatmosphere\u002Fthe-atmosphere",[53],"UK Met Office"," describe, it is:",[84,85,86,93,99],"ul",{},[87,88,89,92],"li",{},[28,90,91],{},"highest over the equator",", around 16 to 18 kilometres, because the warm tropical air is deep and vigorously convective;",[87,94,95,98],{},[28,96,97],{},"lowest over the poles",", around 8 to 9 kilometres, because the cold polar air is shallow;",[87,100,101,104,105,109],{},[28,102,103],{},"variable day to day",", moving up and down with the passing weather systems, often with a sharp step at the boundary between warm and cold air masses, which is exactly where ",[44,106,108],{"href":107},"\u002Flearn\u002Fjet-stream-and-clear-air-turbulence","jet streams"," and clear-air turbulence are found.",[20,111,113],{"id":112},"why-the-weather-lives-below-it","Why the weather lives below it",[10,115,116,117,120,121,124,125,128,129,132],{},"Almost all of the atmosphere's ",[28,118,119],{},"water vapour"," and ",[28,122,123],{},"vertical mixing"," is in the troposphere, so that is where clouds, rain, thunderstorms and most turbulence form. The tropopause acts as a ",[28,126,127],{},"cap"," on rising air: even a powerful thunderstorm updraught usually runs out of buoyancy when it reaches the stable air at the tropopause and spreads sideways into the flat ",[28,130,131],{},"anvil"," top that gives a mature storm its shape. Above the tropopause the stratosphere is dry, very stable and largely cloud-free, which is part of why the upper cruise levels can be so smooth.",[20,134,136],{"id":135},"a-worked-example","A worked example",[10,138,139],{},"A summer thunderstorm builds through the afternoon and its anvil flattens out at around 40,000 feet. That flat top is not a coincidence: the updraught has driven up to the tropopause, hit the stable stratospheric air above it, and spread horizontally because it can no longer rise. The height of the anvil is roughly the height of the local tropopause, which on a warm day in temperate latitudes can be a few thousand feet above the standard 36,000-foot figure.",[10,141,142],{},"For an airliner cruising at FL360 in winter at high latitude, the same logic runs the other way: the tropopause may be well below the aircraft, so it is already cruising in the stratosphere, in dry, stable, generally smooth air, with the day's weather safely beneath it.",[20,144,146],{"id":145},"common-pitfalls","Common pitfalls",[84,148,149,155,161],{},[87,150,151,154],{},[28,152,153],{},"36,000 feet is an average, not a rule."," The actual tropopause can be far higher near the equator and far lower near the poles, so do not assume the standard figure.",[87,156,157,160],{},[28,158,159],{},"The cap can be overshot."," The strongest storm updraughts briefly punch a dome above the tropopause before collapsing back, so an anvil top is a guide, not a guaranteed ceiling.",[87,162,163,166],{},[28,164,165],{},"Smooth is not always so."," The tropopause and the jet streams that run along it are a favoured zone for clear-air turbulence, so the boundary itself can be rough even where there is no cloud.",[20,168,170],{"id":169},"in-pilot-efb","In Pilot EFB",[10,172,173,174,178],{},"Pilot EFB helps you read the ",[44,175,177],{"href":176},"\u002Flearn\u002Freading-winds-and-temperatures-aloft","winds and temperatures aloft"," and the upper-air forecasts that show where the tropopause and the jets sit, so the cruise picture is part of your briefing rather than an afterthought. A briefing you have already pulled stays readable with no signal; fetching fresh forecasts 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":180,"searchDepth":181,"depth":181,"links":182},"",2,[183,184,185,186,187,188],{"id":22,"depth":181,"text":23},{"id":66,"depth":181,"text":67},{"id":112,"depth":181,"text":113},{"id":135,"depth":181,"text":136},{"id":145,"depth":181,"text":146},{"id":169,"depth":181,"text":170},"2026-06-22","What the tropopause is, why it sits higher over the equator than the poles, and why nearly all the weather a pilot deals with happens in the troposphere below it.",false,"md",[194,197,200],{"q":195,"a":196},"What is the tropopause?","The tropopause is the boundary between the troposphere, the lowest layer of the atmosphere where temperature falls with height, and the stratosphere above it, where temperature stops falling. It is defined as the level where the steady cooling with height ends. In the standard atmosphere it sits at 11 kilometres, about 36,000 feet, with a temperature of about minus 56.5 degrees Celsius.",{"q":198,"a":199},"Why does the tropopause height vary?","It is highest over the equator, around 16 to 18 kilometres, because the warm tropical air is deep and convective, and lowest over the poles, around 8 to 9 kilometres, because the cold polar air is shallow. It also moves day to day with the weather. The standard-atmosphere value of about 36,000 feet is a mid-latitude average, not a fixed height.",{"q":201,"a":202},"Why does most weather happen below the tropopause?","Almost all of the atmosphere's water vapour and vertical mixing is in the troposphere, so that is where clouds, rain, thunderstorms and most turbulence form. The tropopause acts as a cap: rising convection, even a strong thunderstorm, usually flattens out into an anvil when it reaches it. Above the tropopause the stratosphere is dry, stable and largely cloud-free.",null,[205,206,207,208],"The tropopause is the boundary where the steady cooling of the troposphere ends and the stratosphere begins.","In the standard atmosphere it sits at 11 kilometres, about 36,000 feet, at about minus 56.5 degrees Celsius.","It is highest over the equator (16 to 18 km) and lowest over the poles (8 to 9 km), and it shifts with the weather.","Nearly all weather lives in the troposphere below it; the stratosphere above is dry, stable and largely cloud-free, and the tropopause caps convection.",{},true,"\u002Flearn\u002Fthe-tropopause",[213,222,230],{"q":214,"options":215,"answer":220,"explanation":221},"In the ICAO standard atmosphere, at roughly what height does the tropopause sit?",[216,217,218,219],"About 18,000 feet","About 11 kilometres, around 36,000 feet","About 50,000 feet","About 5 kilometres",1,"The ICAO standard atmosphere places the tropopause at 11 kilometres, about 36,000 feet, with a temperature of about minus 56.5 degrees Celsius.",{"q":223,"options":224,"answer":220,"explanation":229},"Where is the tropopause highest?",[225,226,227,228],"Over the poles","Over the equator","It is the same height everywhere","Over the oceans only","The tropopause is highest over the equator, around 16 to 18 kilometres, where the warm tropical air is deep, and lowest over the cold poles.",{"q":231,"options":232,"answer":220,"explanation":237},"Why does most weather occur in the troposphere rather than above the tropopause?",[233,234,235,236],"Because the stratosphere is too cold for any air","Because nearly all the water vapour and vertical mixing is in the troposphere, while the stratosphere is dry and stable","Because aircraft cannot fly above the tropopause","Because the tropopause blocks sunlight","The troposphere holds almost all the atmosphere's water vapour and vertical motion, so clouds and storms form there; the stratosphere above is dry, stable and largely cloud-free, and the tropopause caps rising convection.",{"title":5,"description":190},[240,242,244],{"label":241,"url":51},"ICAO Doc 7488: Manual of the ICAO Standard Atmosphere",{"label":243,"url":73},"FAA Aviation Weather Handbook (FAA-H-8083-28B)",{"label":245,"url":79},"UK Met Office: What is the tropopause?","learn\u002Fthe-tropopause","Weather","86SwF-FGmpvDoJ4voeg17K-BB1gt4ogIbeNjAEsLMe0",{"related":250,"newer":264,"older":269,"series":203},[251,256,260],{"path":252,"title":253,"description":254,"date":189,"topic":247,"draft":191,"minutes":255,"series":203,"seriesOrder":203},"\u002Flearn\u002Fcloud-types-explained","Cloud types and what they tell a pilot","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.",3,{"path":107,"title":257,"description":258,"date":189,"topic":247,"draft":191,"minutes":259,"series":203,"seriesOrder":203},"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":261,"title":262,"description":263,"date":189,"topic":247,"draft":191,"minutes":259,"series":203,"seriesOrder":203},"\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":265,"title":266,"description":267,"date":189,"topic":268,"draft":191,"minutes":259,"series":203,"seriesOrder":203},"\u002Flearn\u002Fthe-missed-approach-and-go-around","The missed approach and the go-around","The difference between a go-around and a published missed approach, when each is flown, the default climb gradient that protects the procedure, and why deciding to go around early is a sign of good judgement rather than failure.","Operations",{"path":270,"title":271,"description":272,"date":189,"topic":268,"draft":191,"minutes":259,"series":203,"seriesOrder":203},"\u002Flearn\u002Ftransition-altitude-and-transition-level","Transition altitude and transition level","Where altitudes give way to flight levels, why pilots swap between the local QNH and the standard 1013 pressure setting, and the simple rule for when to change the altimeter climbing and descending.",1782089963902]