Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

5.2Chapter 5: The Earth in Space

Our planet: seasons — Alhussan Physics - Stage 7 Revision Notes & Topical Questions

5 min read 8 parts Lesson 2 of 11 1 quiz

📚 Alhussan Physics - Stage 7 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

5.2 Our planet: seasons — Axial Tilt (23.5°) and Solar Hemisphere Heating — Alhussan International Academy — Physics (Stages 7–9) notes: Explain how the tilt of the Earth's axis causes seasons, changes in day length, temperature and the height of the Sun in the sky.Orbit — the Ea…

  • Near the poles
  • Near the equator
  • Changing day length
  • Over the year
  • Summer in the north
  • Winter in the south

Part 1 of 6The year and the seasons

1Orbit
  • Orbit the Earth orbits the Sun once every year, or 365 days.
2Seasons
  • Seasons the year is divided into spring, summer, autumn and winter.
3Near the poles
  • Near the poles countries have a big difference in weather between summer and winter, with longer, warmer days in summer and shorter, colder days in winter.
4Near the equator
  • Near the equator countries between the Tropic of Cancer and the Tropic of Capricorn do not notice much change.
5Changing day length
  • Changing day length in most places the length of the day changes over the year,
  • so the Sun sets earlier each night as winter approaches and later each night as summer approaches.

Part 2 of 6The tilt of the Earth's axis

1Tilt
  • Tilt the axis is tilted by an angle of 23.5°, and this angle does not change.
  • It always points to the same place in space as the Earth orbits.
2Over the year
  • Over the year for 6 months the North Pole is tilted towards the Sun, and for 6 months it is tilted away.
3Summer in the north
  • Summer in the north the North Pole is tilted towards the Sun, so the northern hemisphere receives more direct sunlight.
  • The Sun stays in the sky for longer each day as the Earth spins, so the day is longer than the night.
4Winter in the south
  • Winter in the south at the same time the southern hemisphere is tilted away from the Sun.
  • The Sun stays in the sky for less time each day until midwinter.
5Six months later
  • Six months later the situation is reversed, so the hemispheres have opposite seasons.
6What the tilt explains
  • What the tilt explains different day lengths, different temperatures and the varying height of the Sun in the sky in summer and winter.

Part 3 of 6Changing temperature

Why summer is hotter
  • Why summer is hotter the Sun is in the sky for longer, and the rays from the Sun are concentrated over a smaller area.
Rays at 90°
  • Rays at 90° if the rays hit the surface at 90°, more energy hits each square metre per second,
  • so the surface heats up faster and the air temperature rises more quickly.
Winter
  • Winter the Sun's light is spread over a bigger area, such as 2 square metres instead of 1,
  • so it is less intense, and the days are shorter,
  • so there is less heating.

Part 4 of 6Changing height of the Sun

1Highest at noon
  • Highest at noon during the day the Sun is highest in the sky at noon.
2Over the year
  • Over the year the height the Sun reaches at noon is higher in summer than in winter, again because of the tilted axis.
3Shadows
  • Shadows a fence post makes a shorter shadow at noon in summer than in winter, because the Sun is higher.

Part 5 of 6Midnight Sun and polar night

Midnight Sun
  • Midnight Sun in regions in the north inside the Arctic Circle, such as Finland, Norway and Canada, the Sun does not set in summer,
  • so they are known as the "Land of the Midnight Sun".
  • The same happens in Antarctica during its summer, but no one lives there to see it.
Polar night
  • Polar night in winter in these places the Sun does not rise at all.
FeatureSummer (tilted towards Sun)Winter (tilted away)
Sun at noonHighLow
Day lengthLonger than nightShorter than night
HeatingMoreLess

Part 6 of 6A common misconception

Distance from the Sun
  • Distance from the Sun some people think it is hotter in summer because the Earth is closer to the Sun, which is not true.
Orbit
  • Orbit the Earth's orbit is nearly circular, and the Earth is slightly closer to the Sun in January each year.
No tilt
  • No tilt if the axis was not tilted, day length would not change over the year and there would be no seasons.

Key terms

TermMeaning
Axisthe imaginary line through the North and South Poles about which the Earth spins.
Tiltthe 23.5° angle of the Earth's axis.
Seasonone of four periods in the year with typical weather and day length.
Hemispherehalf of the Earth, northern or southern.
Arctic Circlethe latitude line around the north where the Sun may not set in summer or rise in winter.
Polar nightwinter in the polar regions when the Sun does not rise at all.

Avoid these mistakes

1
Thinking seasons are caused by the Earth being nearer the Sun — the tilt of the axis causes them.
2
Thinking the Earth's axis wobbles back and forth during the year — it keeps pointing the same way.
3
Thinking the Sun is hotter in summer — its output is the same, but the energy per square metre changes.
4
Thinking the whole Earth has the same season at once — the hemispheres have opposite seasons.

Last updated: