• Tides are the vertical movement of Tides are the vertical movement of water, the rise (flood) and fall (ebb) water, the rise (flood) and fall (ebb) of water in large water bodies. of water in large water bodies.

• Tides are most noticeable along Tides are most noticeable along continental shorelines. continental shorelines.

• Tides occur because the Moon’s Tides occur because the Moon’s gravity changes the shape of gravity changes the shape of Earth’s oceans.Earth’s oceans.

Moon

low tide

High tide

rotation of Earth

• The attraction causes the oceans to The attraction causes the oceans to bulge out in the direction of the bulge out in the direction of the moon. moon.

• Another bulge occurs on the Another bulge occurs on the opposite side, since the Earth is also opposite side, since the Earth is also being pulled toward the moon (and being pulled toward the moon (and away from the water on the far away from the water on the far side). side).

• Since the earth is rotating while this Since the earth is rotating while this is happening, two tides occur each is happening, two tides occur each day. day.

• Spring tide: Spring tide: • A tide of large range occurring A tide of large range occurring

during new and full moons. during new and full moons. • Happens when the Earth, Moon, Happens when the Earth, Moon,

and Sun are all lined up.and Sun are all lined up.• Results in extreme high tides and Results in extreme high tides and

low tides. low tides.

• Neap tide: Neap tide: • A tide of small range occurring A tide of small range occurring

during the 1during the 1stst & 3 & 3rdrd quarter quarter moons. moons.

• Happens when the Earth, Moon, Happens when the Earth, Moon, and Sun are not lined up.and Sun are not lined up.

• Results in less extreme high tides Results in less extreme high tides and low tides. and low tides.