Energy Balance and the Greenhouse Effect

Question 1

Define the solar constant So.

Answer 1

The flux of solar energy incident at the top of the atmosphere per unit area perpendicular to the direction of the Sun.

Question 2

Define Planetary Albedo, α.

Answer 2

The fraction of the total solar energy incident on the planet which is reflected back to space.

Question 3

What reflects solar energy back into space?

Answer 3

Butts, aerosols, bright surfaces, etc.

Question 4

Define Effective Radiative Temperature, T_e.

Answer 4

The temperature of a blackbody which would be in equilibrium with the absorbed (incident-reflected) solar radiation.

Question 5

Define emissivity, ε.

Answer 5

The radiation emitted by a body as a fraction of the radiation that would be emitted by a blackbody at the same temperature.

Question 6

What is Kirchoff’s Law?

Answer 6

The emissitivity of an object must equal its absorpitivity.

Question 7

Recall a diagram of the Leaky Greenhouse Model.

Question 8

What is the top-of-the-atmosphere energy balance for the leaky greenhouse model?

Answer 8

(1-α) * (S₀/4) = (1-ε) * σ * T_s⁴+ ε * α * T_a⁴

or

σ * T_e⁴ = (1-ε) * σ * T_s⁴ + ε * α * T_a⁴

Question 9

What is the surface energy balance for the leaky greenhouse model?

Answer 9

(1-α) * (S₀/4) + ε * σ * T_a⁴ = σ * T_s⁴

or

σ * T_e⁴+ ε * σ * T_a⁴ = σ * T_s⁴