Chapter 3

Question 1

Trade winds are ………….. in winter and are …………….. in summer over ………..

Answer 1

easterlies

westerlies

monsoon areas

Question 2

variation with heigh depends on

Answer 2

meridional temperature gradient

Question 3

Easterlies in winter become ….jet

Answer 3

westerly

Question 4

what winds will exist on upper level:

Answer 4

• winds are westerlies through the year
  
  • atlantic and
  • much of the pacific (E and C)
• high level easterlies
  
  • west pacific
  • indian ocean
  • africa
• Summer monsoon
• NHS summer
• In other areas, the easterlies at higher levels diverge and become westerlies
• the upper level westerlies strengthen and reach jet stream speed to subtropical jet close to 30 N and S

Question 5

In general summer monsoon circulation have

Answer 5

westerlies at low levels

easterlies at high level (middle and upper troposphere)

Question 6

During NH summer

Answer 6

strong easterly winds (E Jet stream) stretch from SE asia to africa

Question 7

TEJ

Answer 7

Tropical easterly Jetstream

(100-200)

Question 8

TEJ are formed

Answer 8

• during NH summer (june to sept/oct)
• over southeast asia to north africa
• between 5 and 20 N
• in the layer between 100-200 hPa

Question 9

TEJ strength:

Answer 9

Its Maximum speed 40-50 m/s

Question 10

westerly jet stream

Answer 10

direct circulation in the west (entrance) and indirect circulation in east (exit) of jet

Question 11

AEJ

Answer 11

african easterly jet

(west african mid trop. Jet)

(600-700)

Question 12

charactaristics of AEJ

Answer 12

• AEJ is formed over N tropical africa and adjoining east atlantic
• found during NHS summer. It is fully developed April - November
• Found between 700 and 600 hPa between 13 and 17 N
• Strongest During west african monsoon (Jan - Sep)
• wind speed 10-25 m/s

Question 13

cause of formation of AEJ

Answer 13

• strong reversal in meridional temperature gradient (increase of temperature from equator towards the pole)
  
  • due to saharn air layer (elevated warm air)/ SAL
    
    • created by saharan desert to the north
  • when AEJ is furthest north (15-20 N) it is maintained by the mechanical effect of the topography, which perturbs (small changes) low level easterlies and results in acceleration of the winds (provides energy for the maintenance) particularly in the lee of the mountains. (provides energy for AEJ)

(THERMAL)

Question 14

Maintenace of AEJ

Answer 14

Mechanical

Question 15

effect of AEJ

Answer 15

• Strong vertical wind shear generated by
  
  • the AEJ and surface monsoon westerlies to help to organize deep convection north and south of the AEJ

Question 16

Tropical easterly Jet is caused by:

Answer 16

• high temperature (cause reversal in meridional temperature gradient)
• upper level anticyclone

over the Tibetan plateau (unique feature)

Question 17

circulations around TEJ:

Answer 17

• east of the Jet/ entrance (direct)
  
  • south east asia
• west of the jet/ exit (indirect)
  
  • North africa

Question 18

effect of TEJ

Answer 18

• Entrance region
  
  • enhance convection over south india and the adjoining ocean
• Exit region
  
  • surpresses vertical motion over near equatorial africa and the atlantic

Question 19

East african low level Jet

Answer 19

somali jet

Question 20

charactaristics of east african low level jet

Answer 20

• maximum wind speeds are found near 850 hPa
• it is a south westerly jet stream (cross equatorial jet)
• it is intense from june to august, with average monthly max speed of 18 m/s (on daily basis the maximum may be 50 m/s)
• maximum wind speed are found north of madagascar and off somali coast
• a split in the axis of the jet over the arabian sea

Question 21

cause of the somali jet:

Answer 21

the southeasterly trades on the northern side of the subtropical high near the mascarene turn to the righ (due to corriolis effect) and blow from the SW to the North of the equator

Question 22

importance of somali jet

Answer 22

feeds moisture to the indian summer monsoon