Why does moon affect tides

During each lunar month, two sets of spring tides and two sets of neap tides occur Sumich, J. When the sun, moon, and Earth are in alignment at the time of the new or full moon , the solar tide has an additive effect on the lunar tide, creating extra-high high tides, and very low, low tides — both commonly called spring tides.

During each lunar month, two sets of spring and two sets of neap tides occur. Just as the angles of the sun, moon and Earth affect tidal heights over the course of a lunar month, so do their distances to one another. Because the moon follows an elliptical path around the Earth, the distance between them varies by about 31, miles over the course of a month.

Once a month, when the moon is closest to the Earth at perigee , tide-generating forces are higher than usual, producing above-average ranges in the tides. Spring tides always happen when the Moon is at the full or new phase, which is when the Sun, Moon and Earth are in alignment. Tides You walk along a beach, seashells, driftwood and seaweed left by the retreating tides at your feet. These bulges create high tides. The low points are where low tides occur.

Download animation It might seem strange that the ocean would bulge on the side farthest from the Moon as well as the side closest to it. Download animation As Earth rotates within this layer of water, its landmasses pass through the two bulges. Our observer sees the tides rise when passing through the bulges, and fall when passing through the low points. The timing and heights of the tide near you will be affected by those additional elements. Download animation Did You Know?

If the sun is unaligned with the moon, then it works against the moon, reducing the high tide and raising the low tide a little bit so the peak and valley are not as large. The process is more complicated the oceans have a shape, different depths and coastlines, so the water sloshes around in ways that causes the sea level to rise and lower by different amounts depending on where you are.

Some locations, like the Bay of Fundy in Canada, see a sea level variation from low to high by as much as 50 feet. In much of the rest of the world, the variation is only a few feet up and down with each high and low tide.

Ellie Webb How does the moon affect the tides?