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Geolens

Case study UK

UK seasonal day length

London to Lerwick

Winter daylight decreases as you travel north from London to Lerwick. Earth’s tilted axis explains both the shorter days and the lower midday Sun.

Meteosat view of Earth's day–night boundary on the December solstice, with more of the Southern Hemisphere in daylight.
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Meteosat-9 SEVIRI, 21 December 2010. The tilted day–night boundary gives the Southern Hemisphere longer days. Axial tilt, rather than a change in Earth–Sun distance, controls this seasonal illumination.
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Location: 51.51°, -0.13°

At the December solstice, London has less than eight hours of daylight while Lerwick has less than six. The difference comes from latitude: northern places follow a shorter path through the illuminated half of Earth when the Northern Hemisphere tilts away from the Sun.

Use the seasons model to compare December with June. Keep the axial tilt fixed and follow each place through a complete rotation. Opposite seasons in Sydney provide a useful check on the idea that Earth’s changing distance from the Sun is the main cause.

Open this state in the lab

Exam-style question

Explain why Lerwick’s December day is shorter than London’s, using axial tilt rather than distance from the Sun.

Teacher hint: Explain how the Northern Hemisphere tilts away from the Sun in December, then compare the daylight arcs at the two latitudes.

Process labs

Why seasons happenSolar altitude and sun path

Sources