Upper Level Winds Flashcards
Cold air - pressure
reduces slowly/ quickly
Quickly
Warm air pressure
reduces slowly/quickly
Slowly
To be a jet stream, the wind has to be greater than blank knots.
70
Whats the jet stream ratio for depth width and length?
1:100:1000
What two jet streams are seasonal?
Tropical easterly and arctic front
What is the height and speed of the polar front jet?
30,000 150-20kts
What is the height and speed of the sub tropic jet? N
40,000 150kts
What is the height and speed of the sub tropic jet? S
40,000 80-90kts
Below the JS core,
temperature colder/harmer when
flying into the polar air
Colder
Above the JS core,
temperature colder/warmer when
flying towards polar air
Warmer
Polar front jet lies closer to the blank front than the blank front.
Cold - warm
What is the season, altitude and speed of the arctic front jet?
January 20000 80kts
What is the season, altitude and speed of the tropical eastily jet?
Summer 50,000 90kts
The most severe
CAT is found near
the frontal zone,
especially at the
higher levels on the
cold/warm side and just
above/below the core
Cold - below
Jet streams have to be X kts to be displayed on a significant weather chart.
80
Low level jet streams are located between x and x feet.
500 and 5000ft
From summer to winter the average geographic position of the polar front jet stream over the North Atlantic moves.. towards the north/south and the speed increases/decreases.
South increases
Jet streams’ altitudes:
-blank Jetstream = 20,000ft
-blank Jetstream = 30,000ft
-Sub-blank Jetstream = 40,000ft
-blank Jetstream = 50,000ft
Jet streams’ altitudes:
-Arctic Jetstream = 20,000ft
-Polar Jetstream = 30,000ft
-Sub-tropical Jetstream = 40,000ft
-Equatorial Jetstream = 50,000ft
Which of the following is correct regarding a warm anticyclone? It increases/decreases in intensity at higher altitudes.
Increases
Therefore, in the Northern Hemisphere, wind veers/backs with decreasing altitude (meaning that winds will veer/back as we climb through the friction layer).
Back then veer
What is the approximate speed of a 40-knot wind, expressed in m/s?
20ms
An aircraft is approaching an airfield when the pilots notice that the headwind is becoming increasingly a crosswind from the right less than 4 500 ft above the airfield. What hemisphere does this occur in?
Southern
Near the surface, friction increases/decreases the wind speed, this which directly increases/decreases the Coriolis force.
Decreases
Strongest clear air turbulence is to be expected.. on the cold/warm side of the jet-stream.
Cold
The north-south horizontal blank gradient at the polar front is the main reason for the formation of the polar front jet stream,
Tempurature
PGF = CF + Centrifugal Force in a high/low
Low
CF = PGF + Centrifugal Force in a high/low
High
The Centrifugal Force acts in the same direction as the PGF ⇒ Increasing wind speed. Therefore, for the same isobar spacing, gradient wind speed in a HIGH is less/greater than the equivalent geostrophic wind.
Greater
In the Northern Hemisphere and over oceans, the surface wind backs by Xº from the geostrophic wind and speed reduces to blank% of the geostrophic wind.
10 degrees 70%
In the Northern Hemisphere and over land, the surface wind backs by Xº compared to the geostrophic wind and speed is reduced by C%.
30degrees. 50%
What is the minimum speed for a wind to be classified as a jet stream?
70kts
Which force causes the surface wind, in the northern hemisphere, to deflect to the left compared to the geostrophic wind? (Pressure gradient/frictional/Coriolis/centrapetal)
Frictional
During a flight you enter a zone of lee waves which causes moderate turbulence. You decide to continue the flight and try to avoid the standing waves by: increasing/decreasing speed whilst flying parallel/perpendicular to the mountains,
Decreasing and perpendicular
What occurs when the isobars are curved?
Geostrophic wind.
Distinguish between katabatic and anabatic winds. The anabatic wind flows upslope and is weaker/stronger compared to the katabatic wind, which flows _____.
Weaker downslope
Coriolis Force (CF) - is the force caused by the rotation of the earth. It is directly proportional to the sine of what?
Latitude
For a given pressure gradient force, the geostrophic wind speed blank as latitude decreases.
Increases
During the cruise at FL270, on a northerly heading from Paris to London, there is a strong crosswind from the right. Which of the following statements is correct regarding the aircraft’s altitude?
Increases
