User interface language: English | Español

Date May 2012 Marks available 3 Reference code 12M.2.SL.TZ1.2
Level Standard level Paper Paper 2 Time zone Time zone 1
Command term Calculate and Explain Question number 2 Adapted from N/A

Question

This question is about the greenhouse effect.

The following data are available for use in this question:

Explain why the power absorbed by the Earth is

P4πd2×(1α)×πr2P4πd2×(1α)×πr2

[3]
a.

The equation in (a) leads to the following expression which can be used to predict the Earth’s average surface temperature T.

T=4(1α)P16πσd2T=4(1α)P16πσd2

(i) Calculate the predicted temperature of the Earth.

(ii) Explain why the actual average surface temperature of the Earth is in fact higher than the answer to (b)(i).

[4]
b.

Markscheme

intensity of the Sun’s radiation at the Earth’s orbit =P4πd2P4πd2;
fraction absorbed by the Earth =(1-∝);
the surface area of the disc (absorbing the radiation) =πr2=πr2;
Look for statements that correctly describe each term.

a.

(i) correct substitution;
to get T=250 (K);

(ii) greenhouse gases in the atmosphere absorb some of the energy radiated by the Earth;
and radiate some of it back to the surface of the Earth;

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 8: Energy production » 8.2 – Thermal energy transfer
Show 82 related questions

View options