// lecture 15

Question 1

real mean meridional circulations

Answer 1

• mostly one cell from summer to winter hemisphere in solstice seasons.
• in annual mean, southern hemisphere cell is larger.
• ITCZ is in NH most of the time.

Question 2

hadley cell engine

Answer 2

• latent energy is converted to potential energy in ITCZ clouds.
• potential energy moves poleward in upper Hadley circulation.
• sun evaporates water.
• air sinks as radiative cooling removes energy.
• dried air returned to surface layer.
• water vapor moves toward equator in trade wins.

Question 3

why do we have jet streams?

Answer 3

because of angular momentum conservation.

Question 4

angular momentum equation

Answer 4

AM = mass * speed * moment arm

Question 5

speed

Answer 5

AM/(mass * distance)

Question 6

poleward flow conserving angular momentum gives

Answer 6

westerly winds: same direction as planet.

Question 7

speed of dirt at equator due to rotation of Earth

Answer 7

2pi radians per day * 6370 km = 465 m/s = 1040 mph

Question 8

earth’s angular moment cycle

Answer 8

• from earth to atmosphere in Easterlies

- from atmosphere to earth in Westerlies

Question 9

the earth must have bands of Easterly (tropics) and Westerly (midlatitudes) zonal mean winds so that

Answer 9

the momentum balance can be maintained. otherwise the atmosphere would slow down or speed up and no maintain a steady climate.

Question 10

a monsoon climate

Answer 10

is usually in the tropics. it has a rainy and dry season, usually with a change in wind direction.

Question 11

Sahara: Ghardai, Algeria 32 N

Answer 11

dry with oasis, springs, but almost no rain.

Question 12

Agadez and Tanout, Niger 16 N

Answer 12

sahel region, sparse grass and bush, summer rain.

Question 13

Bondo, Zaire 4 N

Answer 13

congo basin rainforsest.

Question 14

aridity

Answer 14

mostly subtropics and downwind of mountains.

Question 15

sinking motion in the subtropics causes

Answer 15

deserts to be common in those latitudes.

Question 16

the equator

Answer 16

is wetter.

Question 17

the ocean

Answer 17

• massive: the mass of the atmosphere equals that of about 10 meters of ocean; 30 ft down the pressure is double the surface pressure. ~4000 m deep.
• dark: absorbs a lot of solar radiation.
• wet evaporates to provide source of moisture for land hydrology.
• absorbs and emits important chemicals, e.g. CO2.

Question 18

atmopshere is ___ at the ____ and the ocean is ____ at the _____

Answer 18

hot, bottom; hot, top

Question 19

takes a lot of energy to change ocean

Answer 19

temp. compared to land. so the seasonal cycle of surface temp. over ocean is small compared to land.

Question 20

density of saltwater depends on

Answer 20

salinity and temp.

Question 21

salinity

Answer 21

salt content in parts per thousand.

Question 22

fresh water has its maximum density at

Answer 22

4 degrees C