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0927 Question

1. Tidal

What: regular rise and fall of sea level caused primarily by the gravitational interactions between Earth and Moon, Sun

Force:

  • Gravitation

    • Moon pull on Earth, the strongest, result one bulge

    • Earth pull toward moon, result another bulge

    • Sun. weaker, but strong enough to influence

  • Centrifugal(离心力)

Pattern

  • Semi-diurnal: 半日潮, two high tide and two low tides with same height each lunar day (24hr 50 min)
    • happen in many location like UK
  • Diurnal: 日潮, one high tide and one low tide each lunar day
    • happen in the Gulf of Mexico
  • Mixed: two high and two low with different heights