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IB Physics HL B.2 Greenhouse Effect Question Bank

Practise IB Physics HL B.2 by quantifying radiative balance and analysing molecular infrared absorption, re-emission and feedback evidence.

Syllabus
First assessment 2025
Course
Physics HL
Level
HL

Exam points

  • Calculate absorbed solar power with geometry and albedo, then track energy through the atmosphere.
  • Use emissivity and Stefan–Boltzmann relationships to test surface and atmospheric temperatures.
  • Interpret infrared absorption, re-emission and feedback mechanisms in extended HL data.

Covered syllabus points

B.2.1—Conservation of energyB.2.2—EmissivityB.2.3—AlbedoB.2.4—Earth’s albedo variationB.2.5—Solar constant SB.2.6—Mean solar intensityB.2.7—Greenhouse gasesB.2.8—Infrared absorptionB.2.9—Greenhouse modelsB.2.10—Enhanced greenhouse effect

B.2 Greenhouse effect question 1

[Maximum number: 1]

The diagram shows a simple model of the energy balance in the Earth surface-atmosphere system. The intensities of the radiations are given.

Figure for Question B.2 Greenhouse effect question 1 — IB Physics HL

What is the average intensity radiated by the atmosphere towards the surface?

A

100Wm−2100 \mathrm{Wm}^{-2}

B

150Wm−2150 \mathrm{Wm}^{-2}

C

240Wm−2240 \mathrm{Wm}^{-2}

D

390Wm−2390 \mathrm{Wm}^{-2}

B.2 Greenhouse effect question 2

[Maximum number: 8]

The diagram shows a simplified energy-balance model for the Earth surface-atmosphere system.

Figure for Question B.2 Greenhouse effect question 2 — IB Physics HL

The following data are given:

 Average albedo of Earth =0.30 Average global temperature of the surface =288 K Average Earth-Sun distance =1.5×1011 m\begin{aligned} \text { Average albedo of Earth } & =0.30 \\ \text { Average global temperature of the surface } & =288 \mathrm{~K} \\ \text { Average Earth-Sun distance } & =1.5 \times 10^{11} \mathrm{~m} \end{aligned}

Question (a)

(a)

State what is meant by the solar constant.

The diagram shows a simplified energy-balance model for the Earth surface-atmosphere system.

The following data are given:

[ 1 ]

Question (b)

(b)

Outline the physical mechanism by which some of the radiation emitted by the surface is absorbed by greenhouse gases in the atmosphere and re-radiated towards the surface.

[ 2 ]

Question (c)

(c)

Show that the average global intensity of radiation absorbed by the surface is about 240Wm−2240 \mathrm{Wm}^{-2}.

[ 2 ]

Question (d)

(d)

Determine the average intensity re-radiated by the atmosphere towards the surface. Assume that the emissivity of the surface is 0.90 .

[ 3 ]

B.2 Greenhouse effect question 3

[Maximum number: 1]

A planet has an albedo of 0.30 . A simplified energy balance for the planet is shown.

Figure for Question B.2 Greenhouse effect question 3 — IB Physics HL

What is the intensity radiated by the surface of the planet?

A

70Wm−270 \mathrm{Wm}^{-2}

B

90Wm−290 \mathrm{Wm}^{-2}

C

100Wm−2100 \mathrm{Wm}^{-2}

D

130Wm−2130 \mathrm{Wm}^{-2}

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