// lecture 16

Question 1

topography (orography) and hyrdrology

Answer 1

tends to be wet on the upwind side of mountains and dry on the downwind side of mountains.

Question 2

only about the first meter of soil is involved in

Answer 2

storing heat for a 365 day period - the annual cycle.

Question 3

over the ocean, because it is a fluid, only the first

Answer 3

200-300 m of ocean is involved in storing heat during the annual cycle, much greater mass and heat-storing capability than land or atmosphere.

Question 4

the annual cycle of temp. is larger over

Answer 4

the land than the ocean.

Question 5

freshwater is most dense at 4 C:

Answer 5

• once the deep water is at 4 C, further cooling of the surface makes the surface water less dense than the bottom of the lake.
• thus the cooler water floats on the top and does not mix down.
• this forms ice, a solid, which inhibits heat transport by water turbulence (convection).
• snow falls on ice, which provides good insulation.

Question 6

seawater

Answer 6

continues to increase its density down to -2C, the point at which it freezes.

• mean salinity: 34.7 parts per thousand.
• mean temp: 3.6 C
• mean surface water needs to be fresher than deep water if sea ice can form at the top.

Question 7

oceanic mixed layer

Answer 7

stirred by wind, and surface cooling by evaporation.

• depth very great in North Atlantic, where deep water forms
• shallow in summer hemisphere.
• depth very great in places in Southern Pacific and Indian Ocean.

Question 8

seasonal mixed layer in high altitudes

Answer 8

• seasonal variation in regions of deep winter mixed layer

- North Atlantic and South Pacific off South America

Question 9

deep thermohaline circulation

Answer 9

• takes about 1,000 years to replace the deep water in the ocean from locations in the North Atlantic and Southern ocean
• water comes up in North Pacific
• very old water, low oxygen

Question 10

deepwater formations

Answer 10

to make water dense enough to sink to the bottom it has to be both cool (~2 C) and salty. can be done by:

1) bringing salty water to high latitudes and cooling it down (Norwegian Sea at end of Gult Stream Extension).
2) when sea ice forms, it is at -2 C and the ice crystal formation squeezes out the salt forming brine that can be dense (around Antarctica during ice growth season).

Question 11

anoxic events on continental shelf

Answer 11

sometimes in summer upwelling brings anoxic water (no O2) up onto the continental shelf and kills the bottom dwellers.