The Moon has a powerful influence
The Moon’s gravity pulls on Earth, but the strength of that pull differs across the planet. Along with the motion of the Earth–Moon system, this creates tidal effects in the oceans. The Sun also contributes, although the Moon is the stronger tide-raising influence.
Why coasts see different tides
As Earth rotates, shorelines move through the changing tide pattern. Many places experience two high tides and two low tides in a lunar day, but the real ocean is more complicated than a simple global model. Coastline shape, water depth, and ocean-basin geography influence local tides.
Spring and neap tides
Near new and full moons, the tidal influences of the Moon and Sun reinforce each other, often producing a larger tidal range. Near the first and third quarter moons, their effects partly offset each other, usually producing a smaller range. These are called spring and neap tides.
Why local predictions matter
A high tide does not necessarily happen exactly when the Moon is overhead. To understand actual water levels at a particular harbor or beach, use local tide tables and observations rather than only the position of the Moon.
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