Tides

Definition The tide is the regular rising and falling of the ocean's surface.

Cause Competing gravitational pull of the Moon and Sun on different regions of the Earth.

Moon Tides The gravitational pull of the moon causes the oceans to bulge out in the direction of the moon. Gravity is pulling the water away from the Earth and toward the moon.

Moon Tides Another bulge occurs on the opposite side of the Earth, because the Earth is rotating. Inertia causes the bulge on the other side on the Earth.

Sun Tides Because the Sun is so far away, it does not have much effect on tides by itself. –Increases the effect of the moon –Weakens the effect of the moon

Spring Tide When the moon is between the sun and the earth (at new moon), the sun’s gravitational pull is in the same direction as the moon’s. The two gravitational forces work together to make extra high high tides and extra low low tides.

Spring Tide When the moon is on the direct opposite side of the sun (full moon). The two gravitational forces work together to make extra high high tides and extra low low tides.

Neap Tide When the moon is in its first quarter or its last quarter, the Sun’s gravitational pull is in perpendicular direction to that of the moon. The sun pulls water away from the areas of high tide to the areas of low tides, resulting in lower high tides and higher low tides.

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