microburst

microburst
The strong downdraft that spreads horizontally just above the ground to form a sharply defined gust front. An aircraft approaching this microburst or gust front may encounter a headwind followed by a strong downdraft and finally end up with a strong tailwind. The area of microburst extends from 3000 to 10,000 ft (1–3 km) and lasts from to 5 to 15 min. An intense microburst could induce wind speeds as high as 150 knots. Microbursts are normally associated with thunderstorms, but there are also “dry microbursts.” In these dry microbursts, precipitation falling from the thunderstorms into the relatively dry air of the lower atmosphere evaporates readily, and the large negative buoyancy thus produced accelerates the air downward, entraining more very dry air. No precipitation reaches the ground, but a microburst wind shear occurs. Airports equipped with an LLWAS (low-level wind-shear alert system) “network expansion,” LLWAS systems integrated with terminal Doppler weather radar (TDWR), and TDWR systems can detect microburst alerts and wind-shear alerts. Controllers will issue the appropriate wind-shear alerts or microburst alerts (e.g., “Runway 28 arrival microburst alert, 45 knot loss 3 mile final”).
An aircraft flying from A to F will experience strong headwinds at positions A and B. It will experience increasing tail winds at position D and E. There would be downdraft at positions B, C, and D. The maximum intensity of downdraft will be at position C.

Aviation dictionary. 2014.

Look at other dictionaries:

  • Microburst —   [ maɪkrəʊbəːst] der, (s)/ s, amerikanische Bezeichnung für eine Fallbö mit geringem Durchmesser (maximal etwa 5 km), die den Start oder Landevorgang von Flugzeugen erheblich gefährden kann. Innerhalb einer kurzen Flugstrecke ist dabei ein… …   Universal-Lexikon

  • microburst — [mī′krō bʉrst΄] n. a type of localized downdraft, often associated with thunderstorms, producing very strong, short lived wind shears …   English World dictionary

  • Microburst — Illustration of a microburst. Note the downward motion of the air until it hits ground level. It then spreads outward in all directions. The wind regime in a microburst is opposite to that of a tornado …   Wikipedia

  • Microburst — Nasser Downburst in Gestalt eines Niederschlagsvorhangs mit Ausfließen am Boden Ein Downburst ist eine schwere Fallböe, die meist bei Gewittern auftritt, aber auch bei Schauern vorkommen kann. Hierfür sind zwei verschiedene Mechanismen… …   Deutsch Wikipedia

  • microburst — /muy kreuh berrst /, n. Meteorol. an intense, localized downdraft of air that spreads on the ground, causing rapid changes in wind direction and speed; a localized downburst. [1980 85; MICRO + BURST] * * * ▪ meteorology  pattern of intense winds… …   Universalium

  • Microburst — Mi|cro|burst [ maikrəubə:st] der; [s], s <aus gleichbed. engl. amerik. microburst zu engl. micro (vgl. ↑mikro...) u. burst »Bruch, Ausbruch«> den Start od. Landevorgang von Flugzeugen gefährdende Fallbö (Luftf.) …   Das große Fremdwörterbuch

  • microburst — noun Date: 1981 a violent short lived localized downdraft that creates extreme wind shears at low altitudes and is usually associated with thunderstorms …   New Collegiate Dictionary

  • microburst — noun A strong downdraft, of less than 2.5 miles in diameter, that can cause damaging winds …   Wiktionary

  • microburst — n. violent and strong localized air current that hits the ground and creates extreme wind shears at low altitudes (generally associated with thunderstorms) …   English contemporary dictionary

  • microburst — noun a sudden, powerful, localized air current, especially a downdraught …   English new terms dictionary

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