Upper Winds Flashcards
Trade Winds are
Westerly winds from subtropical highs that converge at the ITCZ
What causes clouds in the ITCZ/Type of clouds
Formed by convergence of NE/SE trade winds
Cu/CB/Thunderstorms - AS/NS in more stable areas
ITCZ is referred to as
Doldrums
Thermal equator
Equatorial trough
Where can icing be experienced in the ITCZ
16,000 ft upwards
Thermal Winds
Steep pressure gradient
Air flows from warmer air mass towards cold mass
Jet Streams Form and speed
Where warm and cold air masses meet
Forms in warmer air mass below tropopause
Wind speed greater than 60kt
Upper Easterly Wind
NH with back to wind cooler air on your left and heat equator on your right
SH with back to wind cooler air on your right and heat equator on your left
Easterly wind not that strong due to not a strong temperature variation between heat equator and equator
SEASONAL
Jet Stream Dimensions
2nm deep
200nm across
2000nm long
1:100:1000
Sub tropical Jet stream Latitude/height/wind speeds
Permanent
Boundary of Hadley and ferrel cell
Move from west to east
30/40N/S
(40,000ft)
150kt in NH
80-90kt in SH
Polar Front Jet Stream
Ferrel cell to polar cells
40 to 65N
50S (strongest in July)
30,000ft always below tropopause
Becomes faster in the winter
Permanent
No annual variation in latitude in south hemisphere
ArtIc Front Jet Stream
60N only
20,000ft in January
Forms between artic and polar air
Tropical Easterly Jet
Seasonal jet
Only in NH
Warmer continental air in north than cooler oceans in south
Found between 10/20 degrees north
45,000ft
Where is CAT worse
On the cold side of the jet stream
Side of the jet adjacent to the old air and just below jets core
Never within the core
Above the core what happens to temp
Subtropical air is cooler at tropopause therefore temp would increase from warm to cold
Change Bars of Sigwx chart show
//
Change bars indicate change of 20kt or 3000ft
Visible indicators associated with jet streams
Cirrus cloud streaks
CAT Turbulence is
Clear Air Turbulence
Severe turbulence occurring in cloudless/clear skies region that can cause severe turbulence
Jet streams
What time of year are polar front jet streams over South Pacific strongest?
Jet streams are typically strongest in winter.
July in SH
Tropical Easterly Jet
Season easterly jet - 10/20N
Core between FL450/FL500
Flow towards the equator
Caused by summer air over equatorial ocean being cooler than land
Over South Asia/South India towards central Africa
Jet Streams Altitudes
Artic Jetstream - 20,000ft
Polar Jetstream - 30,000ft
Sub tropical - 40,000ft
Equatorial - 50,000ft
Clear Air Turbulence
The Erratic movement of air in the absence of any significant visual clues is caused by bodies of air moving at very different speeds
Change bars on jet stream
Two thin lines on jet core line
20kt+- and change of height of 3000ft
