Lectures 7&8: The Atmosphere and Global Heat Budget, The Greenhouse Effect

Question 1

How many Milankovitch Cycles are there?

Answer 1

Three: Eccentricity, Tilt, Precession

Question 2

What is Eccentricity?

Answer 2

The change in Earth’s orbital path (from more circular to more oval-like/elongated vs. circular), when it is elongated it receives more variation in energy

Question 3

How many periods does eccentricity have?

Answer 3

Three: 96k, 125k, 400k years

Question 4

What are the driving forces for the ocean and atmospheric circulation?

Answer 4

-wind-driven ocean circulation, energy transfer (wind stress), albedo & thermal inertia, heat budget and transfer
-evaporation, conduction, radiation, precipitation

Question 5

What is heat flux? What are the units?

Answer 5

amount of items per unit area per unit time, radiation: watts/m2

Question 6

What is the solar heat flux?

Answer 6

342 watts/m2 (top of the atmosphere)

Question 7

What is the geothermal heat flux?

Answer 7

0.075 watts/m2 (bottom of the atmosphere), almost negligible

Question 8

What is black body radiation?

Answer 8

all objects emit electromagnetic energy proportional to temperature
-Sun emits way more than Earth & universal background radiation
-not all true ‘black bodies’

Question 9

How is the troposphere only weakly density stratified?

Answer 9

heat from the bottom, colder/denser air is on the top, warmer/lighter air is on the bottom, lots of mixing occurs in the troposphere (high & low pressure systems)

Question 10

How is the stratosphere strongly density stratified?

Answer 10

heated from above, colder/denser air below warmer/lighter air

Question 11

What is the result when you combine the three Milankovitch Cycles?

Answer 11

glacial periods

Question 12

What is the formula that equals the amount of heat absorbed by the Earth?

Answer 12

= S0 (solar constant) * (1-albedo) * πr2

Question 13

What is the formula for heat radiated from Earth’s surface?

Answer 13

= (e * σ * k4)* 4πr2

Question 14

Why is there a wet lapse rate?

Answer 14

Earth is not a true black body, wet lapse rate = 6.5℃/km

Question 15

What is the Greenhouse Effect?

Answer 15

an atmosphere is able to trap warmth in, leading to a warmer planet than without it, trap IR radiation rather than transmit it

Question 16

What is the Stephen-Boltzman relationship?

Answer 16

watts/m2 = E = e σ k4, little e is emissivity (1 in ideal cases)

Question 17

What is the Stephen-Boltzman constant?

Answer 17

σ = 5.67 x 10^-8 Wm-2k-4

Question 18

What is Wien’s Displacement Law?

Answer 18

the idea that as temperature increases the peak energy shifts to a more frequent wavelength

Question 19

What are the three major EM bands we have to know?

Answer 19

ultraviolet (1-400 nm), visible (400-700 nm), infrared (700-100,000 nm)

Question 20

What is axial tilt?

Answer 20

the tilt of Earth’s axis varies between 22.2-24.5, the greater the tile the more solar energy the poles receive

Question 21

How many periods does axial tilt have?

Answer 21

1 period, 41k years

Question 22

What is precession?

Answer 22

a gradual change or “wobble” in the orientation of Earth’s axis that affects the relationship between tilt and eccentricity

Question 23

How many periods does precession have?

Answer 23

3 periods, 19k, 22k, 24k years

Question 24

What is the relative albedo for ice?

Answer 24

20-70%

Question 25

What is the relative albedo for ice?

Answer 25

20-70%

Question 26

What is the relative albedo for the ocean?

Answer 26

2-10%

Question 27

What is the relative albedo for the forest?

Answer 27

6-18%

Question 28

What is the relative albedo for grasslands?

Answer 28

7-25%

Question 29

What is the relative albedo for soils?

Answer 29

10-20%

Question 30

What is the relative albedo for desert sand?

Answer 30

35-45%

Question 31

What is the relative albedo for fresh snow?

Answer 31

70-80%

Question 32

What type of radiation is inputted into the Earth?

Answer 32

short wave solar radiation

Question 33

What type of radiation is output from the Earth?

Answer 33

long wave

Question 34

Rank the major greenhouse gases

Answer 34

Water vapor (36-72%), carbon dioxide (9-26%), methane (4-9%), ozone (3-7%)