Chapter 3 (lecture)

Question 1

At low levels, Trade-Wind flows predominate, originating in the sub-tropical high-pressure systems (the ‘doldrums’) centered near

Answer 1

30°N and 25° S.

Question 2

However, significant reversals in the low-level wind flow occur over and around

Answer 2

the tropical continents during the change from winter to summer.

Question 3

There is a major cross-equatorial flow from

Answer 3

the southern Indian Ocean to the central Arabian Sea, which reaches maximum speed near 850 hPa is the well known low level Somali jet

Question 4

t upper levels, tropical winds are often relatively

Answer 4

light

Question 5

Summer monsoon circulations have westerlies at low levels, but easterlies at middle- and upper-tropospheric levels, which strengthen as

Answer 5

the troposphere warms and deepens

Question 6

The upper-level westerlies strengthen and may reach jet stream strength to form the sub-tropical jet stream (STJ) along the poleward edge of the tropical air mass, close to 30°N and 30° S

At medium levels, winds of moderate strength often form

Answer 6

wave trains, known as easterly waves, which form in response to temperature differences and convective development

Question 7

If the meridional temperature gradient exists from the surface to higher levels in the troposphere, the corresponding zonal wind continues to

Answer 7

increase with height, reaching jet stream speed near the tropopause

Question 8

For the geostrophic wind in zonal direction, the thermal wind equation can be expressed as:

Answer 8

Question 9

Thus, according to the thermal wind equation, when the temperature decreases polewards,

Answer 9

the westerly wind increases with height

Question 10

The formation of jet streams can be explained by using the

Answer 10

thermal wind equation, which gives the relationship between the vertical shear of the geostrophic wind and the horizontal temperature gradient

Question 11

During the south Asian summer monsoon, the TEJ induced

Answer 11

secondary circulations that enhance convection over South India, the Maritime Continent, and nearby ocean, while suppressing upward motion in its exit region over the near equatorial Africa and the Atlantic

Question 12

TEJ

It is believed that the jet may be caused by the uniquely

Answer 12

high temperatures and heights over the tibetan plteau during summer

Question 13

Meridional heating surplus helps to

Answer 13

establish upper level high pressure over the plateau and strong easterlies over central and southern india