ウィンドシア
A sudden change in wind speed and/or direction over a short distance, hazardous during takeoff and landing.
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Meteorology
Browse Meteorology terms for pilots, air traffic controllers, cabin crew and aviation learners.
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クリアアイシング
The formation of smooth, transparent ice on aircraft surfaces, resulting from slow freezing of large supercooled water droplets.
View termシグニフィカントウェザー図
A meteorological chart that displays forecasted significant weather phenomena, including turbulence, icing, and cumulonimbus clouds, relevant for flight safety at specific flight levels.
View termシグニフィカント気温層
A specific altitude or flight level at which temperature changes are forecast to be significant for flight operations, affecting aircraft performance, icing risk, or fuel management.
View termジェット気流
A narrow, fast-flowing air current in the upper atmosphere, typically between 20 000 and 50 000 ft, affecting cruise performance.
View termスキューティーログピー図
A thermodynamic diagram used in meteorology to plot atmospheric soundings, displaying temperature, dew point, and wind profiles with altitude to assess atmospheric stability and forecast weather hazards.
View termスコール
Sudden increase in wind speed of at least 15 knots, sustained for at least one minute.
View termスノータム
Special NOTAM issued when snow, ice or slush significantly affects aerodrome movement areas.
View termターミナル飛行場気象予報
A concise statement of the expected meteorological conditions at an aerodrome for a specified period.
View termホールドオーバー時間
Estimated time fluid will prevent ice before need for re‑application.
View termマイクロバースト
A small, intense downdraft producing damaging winds near the ground, hazardous to aircraft during takeoff or landing.
View termライムアイシング
The formation of rough, milky, opaque ice due to rapid freezing of supercooled water droplets on aircraft surfaces.
View termローター雲
A turbulent, low-level cloud formation found downwind of mountain ranges, forming in the rotor zone beneath and near mountain waves; indicative of severe turbulence and hazardous for aviation.
View term上空の風と気温メッセージ
A meteorological report providing forecasted wind direction, wind speed, and temperature at specific altitudes above mean sea level, used for flight planning and fuel calculations.
View term中程度の乱気流
Turbulence that causes changes in altitude and/or attitude but aircraft remains in control; occupants may feel strain against seat belts.
View term乱気流
Irregular atmospheric motion caused by eddies and vertical currents, affecting aircraft stability, comfort, and sometimes control.
View term予報図
A weather chart produced by meteorological authorities that forecasts the expected positions of pressure systems, fronts, and significant weather for a specified future time.
View term低気圧
An area of the atmosphere where the pressure is lower than that of the surrounding region, often associated with unsettled weather, precipitation, and potential turbulence.
View term低高度ウィンドシア
Wind shear occurring below 2 000 ft AGL, especially hazardous during takeoff and landing phases.
View term低高度飛行域のエリア予報（GAMET）
A GAMET area forecast describing significant weather below FL100 (or FL150 over mountainous terrain) within a FIR, supporting VFR and low-level IFR planning.
View term優勢視程
Greatest visibility value equaled or exceeded for at least half the horizon.
View term制動性能
Pilot- or airport-reported assessment of runway surface stopping quality: good/medium/poor/nil.
View term国際標準大気
A model of the atmosphere based on standard average conditions at sea level, used for calibrating instruments and performance calculations. Defined by ICAO: 15°C, 1013.25 hPa, and lapse rate of 2°C per 1000 ft.
View term国際標準大気からの逸脱
The difference between the actual atmospheric temperature and the standard temperature defined by the International Standard Atmosphere at a given altitude.
View term地上解析図
A weather chart depicting current meteorological features such as pressure systems, fronts, and precipitation areas at the Earth's surface; essential for flight planning and enroute weather briefing.
View term埋没積乱雲
Cumulonimbus cloud obscured within other cloud layers, not visually identifiable, but with severe turbulence and precipitation.
View term大気サウンディング
A vertical profile of the atmosphere obtained by balloon or remote sensing, recording temperature, humidity, wind, and pressure at various altitudes for weather analysis and flight planning.
View term定在性レンズ雲
A smooth, lens-shaped cloud that forms at high altitudes in the crest of mountain waves; often stationary, and indicative of significant atmospheric turbulence downwind of mountain ranges.
View term寒冷前線
A weather front where a cold air mass advances and displaces a warmer air mass, often producing showers, thunderstorms, and abrupt changes in wind and temperature.
View term対流圏界面
The boundary layer between troposphere and stratosphere, marked by a temperature inversion, affecting flight levels and turbulence potential.
View term山岳波
A standing atmospheric wave created when stable air flows over a mountain or ridge, often causing turbulence and rotor clouds.
View term強い乱気流
Turbulence that causes large, abrupt changes in altitude and/or attitude. Aircraft may be momentarily out of control. Occupants are forced violently against seat belts.
View term晴天乱気流
Turbulence occurring in clear skies, typically at high altitudes near the jet stream, with no visible weather phenomena.
View term気圧
The atmospheric pressure as measured by a barometer, used to determine altimeter settings and to ensure altitude accuracy during flight operations.
View term気圧高度
The altitude indicated by a barometric altimeter set to the standard pressure setting of 1013.25 hPa or 29.92 inHg. Used as a reference for aircraft performance calculations.
View term気温逆転
A meteorological condition where temperature increases with altitude instead of decreasing, which can trap pollutants and affect aircraft climb performance.
View term気象気場報告
Routine coded weather observation for a specific aerodrome at a specific time.
View term氷結高度
The lowest altitude in the atmosphere at which the air temperature drops to 0°C (32°F), marking the boundary where liquid water can freeze.
View term汚染滑走路
Runway with >25% surface covered by standing water ≥3 mm, slush, snow, ice.
View term混合氷結
Presence of both rime and clear ice types on aircraft surfaces.
View term温暖前線
A boundary where a warm air mass advances and rises over a retreating cold air mass, usually resulting in steady precipitation and lower clouds along the front.
View term滑走路摩擦
Measurement of friction coefficient between tires and runway; indicates braking performance.
View term滑走路状態報告
Aerodrome-issued report of runway surface condition using RCAM and RWYCC.
View term滑走路視程
Distance over which runway markings or lights are visible from centreline on approach.
View term火山灰重要気象情報
A SIGMET concerning volcanic ash clouds that may affect en‑route flight safety.
View term熱帯低気圧に関する重要気象情報（SIGMET）
A SIGMET issued for a tropical cyclone within or approaching an FIR, including observed or forecast TC position, extent of associated cumulonimbus clouds, movement and intensity.
View term特別気象報告
An unscheduled aerodrome weather report issued when significant meteorological changes occur between routine METARs.
View term着氷
The accumulation of ice on aircraft surfaces due to supercooled water droplets, which can affect aerodynamics and instrument performance.
View term短時間傾向予報（TREND）
A TREND appended to a METAR or SPECI giving expected significant changes in surface wind, visibility, weather or cloud over the next two hours.
View term積乱雲
Towering vertical cloud with significant turbulence, precipitation, and lightning potential.
View term積雲（高い）
Large cumulus cloud with strong vertical development, indicating convective activity, but not yet cumulonimbus.
View term突風
A sudden, brief increase in wind speed, typically varying with rapid fluctuations.
View term自動気象観測システム（AWOS）
An unattended station that continuously measures and broadcasts real-time surface weather elements to pilots and ATC on a discrete frequency.
View term自動飛行場情報放送（ATIS）
A continuous broadcast of recorded aerodrome information, including weather, runways and NOTAMs, provided to reduce controller-pilot communication workload.
View term視程
Greatest distance at which prominent objects are visible and identifiable by day.
View term過冷却大型液滴
Liquid droplets below freezing point that can remain liquid until striking an object.
View term重大気象情報
A weather advisory issued by a Meteorological Watch Office concerning significant en‑route weather hazards affecting flight safety.
View term閉塞前線
A composite weather front formed during the process of cyclogenesis when a cold front overtakes a warm front, leading to complex weather patterns including precipitation and changes in wind direction.
View term防氷
Application of fluid to prevent ice formation during ground operations or flight.
View term除氷
Removal of existing frost, ice or snow from aircraft surfaces before flight.
View term雲底
Lowest altitude of the visible cloud layer, reported as base of scattered, broken, overcast.
View term雲底高度
Height above ground at which an unbroken or overcast cloud layer exists.
View term雷雨
Convective weather event with thunder, lightning, precipitation and possible severe turbulence.
View term風向け矢羽
A graphic symbol used on meteorological charts to represent wind speed and direction at a specific location and altitude, typically shown as a shaft with barbs and pennants.
View term高層天気図
A meteorological chart depicting wind, temperature, and pressure patterns at specified altitudes above the earth’s surface, used to forecast enroute weather conditions for aviation operations.
View term高度計の標準気圧設定
An altimeter setting based on the standard pressure of 1013.25 hPa or 29.92 inHg, used above the transition altitude. Known as QNE in ICAO terminology.
View term高度計の海面気圧設定
The altimeter setting that corresponds to the atmospheric pressure at mean sea level. Referred to as QNH in ICAO phraseology.
View term高度計の飛行場標高設定
The altimeter setting that displays the elevation of the aerodrome as the altitude on the altimeter when on the ground. Referred to as QFE in ICAO terminology.
View term高度計設定値
The current local atmospheric pressure value set in an aircraft’s altimeter to ensure correct indication of altitude above mean sea level, typically given in hectopascals (hPa) or inches of mercury (inHg).
View term高気圧
An area of the atmosphere where the pressure is higher than that of the surrounding region, often associated with stable weather, clear skies, and reduced turbulence.
View term高積雲カステラヌス
Medium-level turreted cloud with rising towers indicating mid‑level instability, possible precursor to thunderstorms.
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