Meteorology Flashcards
What is the definition for Airmet?
AIRMET INFORMATION — Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en route weather phenomena which may affect the safety of low-level aircraft operations and which was not already included in the forecast issued for low-level flights in the flight information region concerned or sub-area thereof.
(P.68)
What is the definition for CEILING (ICAO)?
CEILING (ICAO) — The height above the ground or water of the base of the lowest layer of cloud below 6000m (20,000ft) covering more than half the sky.
(P.75)
What are the 3 types of snow?
a. Dry snow. Snow which can be blown if loose or, if compacted by hand, will fall apart upon release; specific gravity: up to but not including 0.35.
b. Wet snow. Snow which, if compacted by hand, will stick together and tend to or form a snow- ball; specific gravity: 0.35 up to but not including 0.5.
c. Compacted snow. Snow which has been compressed into a solid mass that resists further compression and will hold together or break up into lumps if picked up; specific gravity: 0.5 and over.
(p. 100)
What is SIGMET?
A description in abbreviated plain language concerning the occurrence of specified en-route weather phenomena, which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.
The period of validity of a SIGMET message shall be not more than 4 hours (can be extended to 6 hours on special occasions).
(p.430)
What is AIRMET?
A concise description in abbreviated plain language concerning the occurrence of specified en-route weather phenomena, which may affect the safety of low-level flights, and of the development of those phenomena in time and space. Validity shall not be more than 4 hours.
(p.430)
Jet Stream: at what wind speed the lines of the Jets appear on the maps?
What does it mean when the symbol || (2 vertical lines) appears on the Jet line?
The heavy line delineating the jet axis begins/ ends at the points where a wind speed of 40m/s (80kt) is forecast. Symbol || used whenever the height of the jet axis changes by +/-3000ft or the speed changes by +/-20kt.
(p.456)
CB clouds description: what is the meaning of ISOL, EMBD, OCNL, FRQ?
ISOL = individual CBs (isolated). Spatial coverage less than 50%.
OCNL = well separated CBs (occasional). Spatial coverage 50-75%.
FRQ = CBs with little or no separation (frequent). Coverage>75%.
EMBD = CBs embedded in layers of other clouds or concealed by haze (embedded).
(p.456, 538)
Wind in METAR - is it TRUE or MAG?
True.
p.494
TAF: why, besides the mean wind value, we sometimes have the MAX value as well?
When the forecast maximum speed (gust) exceeds the forecast mean wind speed by 5m/s (10kt) or more, the forecast maximum wind speed shall be indicated.
(p.504)
TAF: what is NSW?
The expected end of occurrence of significant WX phenomena that are described in the TAF should be indicated by the abbreviation “NSW”.
(p.505)
What can be the time period of “BCMG” in the TAF?
Normally 2 hours, but not more than 4 hours.
p.508
TEMPO: how much time can the temporary conditions occur?
Less than one hour, and, in the aggregate, cover less than one-half of the forecast period during which the fluctuations are expected to occur.
(p.508)
Wind direction: what are the criteria for including V (varying) in the METAR?
What is NDV?
When the variation >60 deg, but less than 180 deg, and the speed>3kt.
NDV = no directional variations.
(p.570)
What is the difference between NSC and NCD?
Same meaning. Used when there are no CB/TCU clouds, no restriction on vertical visibility and CAVOK is not appropriate.
NCD is from automated system.
(p.571)
What is CAVOK?
Ceiling And Visibility OK. Replaces visibility RVR, present weather and cloud if:
(1) Visibility is 10km or more;
(2) No cumulonimbus, towering cumulus and no other cloud below 5000ft or below the highest minimum sector altitude, whichever is greater, and
(3) No significant present weather.
(p. 572)
