AQA · GCSE · Physics

    Course version: 8463 · Version from Sept 2016

    (HT only) Students should be able to use information, or draw/ interpret…

    Full specification wording

    Perfect black bodies and radiation: (HT only) Students should be able to use information, or draw/ interpret diagrams to show how radiation affects the temperature of the Earth’s surface and atmosphere.

    This is Higher tier only.

    Checked against the AQA 8463 specification (opens in a new tab) on .

    • Point 6 of 6
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    This is Higher tier only. The standard diagram shows arrows whose widths represent rates of energy transfer: short wavelength radiation arriving from the Sun, part of it reflected straight back to space by clouds, snow and ice, the rest absorbed by the surface and the atmosphere. The warmed surface then emits long wavelength infrared, some of which escapes and some of which is absorbed by greenhouse gases and re-emitted in all directions, including back down. To interpret a diagram, check each arrow for its direction, its wavelength label and its size, then total the energy in and the energy out: equal totals mean a steady temperature, and an excess arriving means the surface warms.

    What earns the marks

    • Identifying incoming short wavelength solar radiation and outgoing long wavelength infrared on the diagram.
    • Identifying radiation reflected back into space without being absorbed.
    • Showing greenhouse gases absorbing infrared and re-emitting some of it back towards the surface.
    • Using the values on the diagram to state whether the temperature will rise, fall or stay constant.

    Common mistakes and how to put them right

    • Drawing the outgoing radiation at the same wavelength as the incoming radiation.

    • Drawing re-emission from greenhouse gases only downwards, never upwards.

    • Leaving the reflected arrow out when totalling the energy arriving and leaving.

    • Concluding the temperature is constant when the numbers on the arrows do not balance.

    Exam tips

    • Label every arrow with its direction and whether it is short or long wavelength.
    • Add up the values entering and leaving before writing any conclusion.
    • This is Higher tier only; diagrams are often marked for arrow direction as much as for wording.

    Try the lesson

    The start of the Perfect black bodies and radiation: (HT only) Students should be able to use information, or draw/ interpret diagrams to show how radiation affects the temperature of the Earth’s surface and atmosphere. lesson, made from checked teaching notes for this specification point.

    Have a go first

    Radiation from the Sun reaches the Earth's surface, and radiation leaving the surface is partly absorbed by gases in the atmosphere. What effect does this absorption by atmospheric gases have on the Earth's surface temperature?

    Listen

    This is Higher tier only. The standard diagram shows arrows whose widths represent rates of energy transfer: short wavelength radiation arriving from the Sun, part of it reflected straight back to space by clouds, snow and ice, the rest absorbed by the surface and the atmosphere. The warmed surface then emits long wavelength infrared, some of which escapes and some of which is absorbed by greenhouse gases and re-emitted in all directions, including back down. To interpret a diagram, check each arrow for its direction, its wavelength label and its size, then total the energy in and the energy out: equal totals mean a steady temperature, and an excess arriving means the surface warms. A strong answer earns marks for these points. identifying incoming short wavelength solar radiation and outgoing long wavelength infrared on the diagram. identifying radiation reflected back into space without being absorbed. showing greenhouse gases absorbing infrared and re-emitting some of it back towards the surface. using the values on the diagram to state whether the temperature will rise, fall or stay constant. Exam tip: Label every arrow with its direction and whether it is short or long wavelength.

    See it

    A top-down flowchart. Short wavelength radiation from the Sun splits into two paths: one goes to clouds, snow and ice, which then leads to reflected back to space; the other goes to surface and atmosphere absorb. From there an arrow leads to warmed surface emits long wavelength infrared, which splits into two: one branch goes to escapes to space, the other to greenhouse gases absorb infrared. That leads to re-emitted in all directions, which splits into back down towards the surface and upwards.
    Shows how incoming short wavelength solar radiation is reflected or absorbed, and how the warmed surface emits long wavelength infrared that escapes or is absorbed and re-emitted by greenhouse gases.

    Key words

    Say what each word means before you turn the card.

    short and long wavelength radiation

    Try answering aloud or in your head before turning the card.

    reflection into space

    Try answering aloud or in your head before turning the card.

    greenhouse gases

    Try answering aloud or in your head before turning the card.

    interpreting arrow sizes

    Try answering aloud or in your head before turning the card.

    See every definition
    short and long wavelength radiation
    Short wavelength radiation arrives from the Sun, while the warmed surface emits long wavelength infrared.
    reflection into space
    Part of the incoming radiation is reflected straight back to space by clouds, snow and ice.
    greenhouse gases
    These absorb infrared and re-emit some of it in all directions, including back down.
    interpreting arrow sizes
    Check each arrow for its direction, its wavelength label and its size, then total the energy in and the energy out.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. Short wavelength radiation from the Sun splits into two paths: one goes to clouds, snow and ice, which then leads to reflected back to space; the other goes to surface and atmosphere absorb. From there an arrow leads to warmed surface emits long wavelength infrared, which splits into two: one branch goes to escapes to space, the other to greenhouse gases absorb infrared. That leads to re-emitted in all directions, which splits into back down towards the surface and upwards.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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