Earth's energy balance

Question 1

What is the temperature of an object dependent on?

Answer 1

Amount of energy it emits and receives

Question 2

How does Earth give out heat?

Answer 2

Radiation (Earth is in a vacuum so can’t conduct heat by conduction or convection)

Question 3

Solar radiation is …

Answer 3

shortwave

Question 4

Terrestrial radiation is…

Answer 4

longwave (infrared)

Question 5

The hotter the object…

Answer 5

The more the spectrum is shifted to short wavelengths

Question 6

What is the average incoming solar flux over all latitudes?

Answer 6

342 Wm^-2

Question 7

What is Earth’s global average albedo?

Answer 7

0.3

Question 8

What would the temperature of the Earth be if there was no atmosphere?

Answer 8

-18ºC

Question 9

How much of a warming effect does the natural greenhouse effect have?

Answer 9

Warming of 33ºC

Question 10

What is emissivity?

Answer 10

The ratio of actually emitted to maximum possible radiation emitted

Question 11

What is the average global emissivity?

Answer 11

0.61

Question 12

What is bare Earth temperature with albedo estimated at?

Answer 12

-18ºC

Question 13

How does the Earth stay in radiative equilibrium when emissivity is decreased?

Answer 13

Earth must radiate at higher temperatures

[E=εσT^4]

Question 14

What temperature would earth be without the heat source of the sun?

Answer 14

-269ºC

Question 15

What is terrestrial radiation?

Answer 15

Thermal radiation emitted by earth

Question 16

What does radiative equilibrium mean?

Answer 16

Energy absorbed by earth is equal to energy emitted by earth to space

Question 17

If earth is in equilibrium with incoming solar radiation, E emitted should be equal. This would make the earth 5ºC. What does this calculation not consider?

Answer 17

Greenhouse effect and the albedo of the earth’s surface and clouds

Question 18

What is albedo?

Answer 18

Reflectivity of solar radiation by earth and the atmosphere

Question 19

Even when the radiative balance equation is solved fairly accurately for each latitude band of Earth, the temperature distribution is still not right. Why?

Answer 19

Ignores the transport of heat by weather systems and ocean circulation, which reduces the temperature contrast