Question

Explain in detail what causes tides and give one reason why it is important for humans to monitor tides. Explain the difference between a NEAP tide and a SPRING tide. (4 points)





(4 points)

Answer 1

What causes tides
- Tides are caused mainly by the gravitational attraction of the Moon and, to a lesser extent, the Sun acting on different parts of the Earth. Because gravity falls off with distance, the side of Earth nearest the Moon feels a stronger pull than the center and the far side feels a weaker pull. That difference in pull (the tidal force) produces two bulges of water, one toward the Moon and one on the opposite side.
- The Earth–Moon system also rotates about its common center of mass, producing a centrifugal effect that helps explain the bulge on the far side. As the Earth rotates under these bulges we experience the regular rise and fall of sea level (usually two high and two low tides each lunar day).

One reason it is important to monitor tides
- Safety and coastal planning: tide forecasts are essential for safe navigation and port operations (knowing when there is enough depth for ships), and for predicting coastal flooding risk—especially when high tides coincide with storms (storm surge) or spring tides, which can cause severe inundation.

Difference between a neap tide and a spring tide
- Spring tide: occurs at new moon and full moon, when Sun, Moon and Earth are aligned. The Sun’s tidal effect adds to the Moon’s, producing the largest tidal range (higher high tides and lower low tides).
- Neap tide: occurs at first and third quarter moons, when the Sun and Moon are at roughly right angles as seen from Earth. Their tidal effects partially cancel, producing the smallest tidal range (lower high tides and higher low tides).
- These alternate on a roughly fortnightly cycle (about every 7–8 days between spring and neap).