Earth's Energy Balance and the Greenhouse Effect, Quantified · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

The missing warmth in Earth's budget

Science · Earth's Systems · ages 16-17
Name ______________________   Date ____________

  1. A simple model balances sunlight against bare radiation. What temperature results?

    • Exactly today's temperature
    • Hotter than today's surface
    • Colder than the world you live in

  2. What two tallies make up Earth's energy budget?

    • Energy arriving from the Sun and energy leaving for space
    • Money spent and money taxed each year
    • Rain falling and rivers flowing to seas

  3. The gap between the model and reality is a clue, not a maths error.

    Circle one:   True   False

  4. Why does a trace gas have such a large effect?

    • Most air lets that glow pass, while trace gases catch it
    • Every air molecule catches infrared equally
    • Infrared never leaves the ground at all

  5. How do gases like carbon dioxide and methane warm the surface?

    • They bounce all sunlight away
    • They absorb outgoing infrared and reradiate some back down
    • They eat clouds before rain forms

  6. Why is Venus around 460 degrees, hot enough to melt lead?

    • It orbits too close to the Sun
    • Its clouds make extra sunlight
    • Its carbon dioxide traps outgoing heat on a huge scale

  7. An energy diagram balances, yet the surface reads warm. What do you conclude?

    • Check that incoming and outgoing terms match, then blame the gap on trapping
    • Add extra sunlight until the numbers look nice
    • Delete the reflected sunlight from the books

  8. The young Sun was dimmer, yet early Earth held liquid water. What explains it?

    • The Sun was brighter, so warmth needs no answer
    • A stronger past greenhouse kept water liquid under a dimmer Sun
    • Physics worked differently billions of years ago
LightMySky · lightmysky.comW1-mt_dDV2fr06nO-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

The missing warmth in Earth's budget W1-mt_dDV2fr06nO-s1

  1. Colder than the world you live in · The simple model without an atmosphere settles below freezing point.
  2. Energy arriving from the Sun and energy leaving for space · The budget is a running tally of sunlight in against infrared out.
  3. True · The mismatch is the clue: something in the air keeps extra warmth back.
  4. Most air lets that glow pass, while trace gases catch it · A tiny fraction of the air does the catching, which is why small gas changes matter.
  5. They absorb outgoing infrared and reradiate some back down · Returned infrared is extra heating the bare model never counted.
  6. Its carbon dioxide traps outgoing heat on a huge scale · Ninety times thicker air made almost fully of carbon dioxide returns heat downward relentlessly.
  7. Check that incoming and outgoing terms match, then blame the gap on trapping · A balanced diagram with a warm surface can only mean the air returns heat downward.
  8. A stronger past greenhouse kept water liquid under a dimmer Sun · The same balance maths that explains today solves the old puzzle too.
Worksheet · LightMySky