EASA ATPL METEROLOGY EXAM 2023-2024 ACTUAL EXAM
300 QUESTIONS AND CORRECT DETAILED ANSWERS
(VERIFIED ANSWERS) |AGRADE
Severe CAT likely to occur when: – ANSWER- wind in jet core > 110
kts
vertical shear > 5 kts / 1000 ft
horizontal shear > 45 kts / 150 NM
„where would you expect to encounter the greatest intensity of CAT
associated with polar jet stream?” – ANSWER- along the axis of the jet
stream core to the left (looking downstream)
aka on the depression side
„CAT should be anticipated when: – ANSWER- a sharp trough area aloft
is present, even though the wind speeds may be considerably less than
that of jet stream winds”
Mountain Waves
favorable conditions: – ANSWER- 1) wind speed > 20 kts at top of mtn
2) wind blows at right angles to mtn range (or within 30° of this)
3) wind speed increases with altitude, but wind direction remains more
or less constant (strong waves are often associated with jet streams)
4) atmosphere stable (preferably stratified in several thin stable layers)
and especially if there is an inversion or isothermal present just above
the level of the mountain top, with less stable air above and below,
between crest level and a few thousand feet above
Rotor – ANSWER- – occur in lower turbulent zone that stretches from
surface downwind of the mountain and up to a height of about 1000-
2000ft above mountain top
- usually first rotor (situated below and generated by first wave) that is
most intense with severe to extreme turbulence - rotor zone center is situated at about same height as mountain top
- if closed circulation is present this will usually show up as a wind
reversal at the surface compared to the wind at height - rotor cloud (aka roll cloud) at top o frotor zone often indicates presence
of a rotor phenomena - looks like a line of small cumulus clouds close together or sometimes
stratus fractus
in arid areas without sufficient moisture for a rotor cloud to form, a dust
or sand might whirl up on the upwind side of the rotor zone (closest to
the mtn) - severe turb -> avoid!
lenticular clouds – ANSWER- stationary and may appear at several
levels - form within stable layers in the crests of mountain waves
- usually appear up to a few thousand feet above mountain crests but can
also be seen at any level up to the tropopause, sometimes even above - airflow through these clouds usually smooth
(unless edges of lenticular clouds appear ragged, indication of moderate
to strong turbulence)
cap clouds – ANSWER- ascending motion on upward / windward side of
mountain and pressure falls around the top and the lee side of the
mountain intensifies condensation and a cloud cap, hiding the top of the
elevated terrain - appears over crest of mountain ridge
- typically form on upwind side of mountain ridge
- strong surface winds can sometimes extend the cap cloud a little bit
further beyond the mountain top over to the downwind (lee-) side of
mountain
this overhang is a good indication of a strong “föhn” wind
if you see a cap cloud on the upwind side of a mountain, the cloud itself
is typically quite harmless, but indication that there is a great possibility
of other, more dangerous mountain wave phenomena (rotor zone, strong
down-draughts as great as 5000 fpm etc) present on the downwind side
mountain wind / katabatic – ANSWER- down, mountain, night, cooling
valley wind / anabatic – ANSWER- up from valley, day, warming
-> Anabatic (arrow upwards)
jet stream ratio – ANSWER- 1:100
temperature relation crossing W-E Jetstream from S-N – ANSWERbelow JS core altitude -> temp falls
at JS core altitude -> temp constant
above JS core altitude -> temp rises
Remember
colder air to left looking downwind => below tropopause => wind speed
increases with height
colder air to right looking downwind => above tropopause => wind
speed decreases with height
equatorial jet stream – ANSWER- – occurs in summer between JUNE
and AUGUST as
result of monsoon climate
- blowing from SE asia through southern india towards central Africa
- position typically around 15°N
- core altitude typically between FL450-500
- speeds typically up to 60 kts, rarely over 100
- ** only major jet stream that is easterly (E=>W)
facts about typical polar front jet stream – ANSWER- – wind accelerates
with increasing alt up to level where temp contrast between air masses is
equalized - at alts above that the wind speed decreases
- steepest pressure surface slope will be at the level where the temp is
the same on both sides of the frontal surface - normally at strongest in area between a trough and ridge
- STRONGEST IN WINTER (south pacific = winter in July)
max wind speed of polar front jet stream found … – ANSWER- on warm
side of frontal zone at altitudes just above the tropopause of the cold air
(about 1000-5000 ft below the warm tropopause)