At the coast, the sea rises and falls with the tides. The Moon and Sun help cause this movement through gravity. The difference between high and low water is not always the same.
Water and oceans · Discover & try
Why does the sea rise and fall?
Reading level 1 of 5 · EarlyChange
Word help
tidal range
The height difference between high tide and low tide.
spring tide
A larger tidal range around new and full Moon.
neap tide
A smaller tidal range around the quarter Moon phases.
Watch · Try · Explain
See how it works
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Idealised spring-neap comparison; sizes and bulges are exaggerated, with no local tide predictions.
What to look for
- The alignment of the three bodies
- The gap between high and low water
- A smaller range that still includes tides
Explain what you noticed
When does the spring-tide pattern occur?
Keep this idea: Alignment affects tidal range; coastal conditions shape local water levels.
Follow the sources
- NOAA National Ocean Service — What are tides?
- NOAA National Ocean Service — Tidal Variations: The Influence of Position and Distance
- NOAA National Ocean Service — What Affects Tides in Addition to the Sun and Moon?
Source material checked 2026-10-28. Explanations and activities by Nepedia. Agency source links do not imply endorsement.
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