TIDES

• The steady rise and fall of the ocean water levels is called the tide.

• Tides are caused by the pull of gravity between the Earth, Moon, and Sun.

• The Moon’s gravitational pull is much stronger on Earth than the Sun’s because the Moon is so much closer to us.

• Earth’s ocean tides are caused by the Moon’s gravitational pull on Earth.

• The Moon’s gravity causes high tides to occur on the parts of Earth that are directly facing the Moon, and facing away from the Moon.

• Low tides occur in the areas that are neither facing nor facing away from the Moon.

• Most places have two high tides and two low tides each day, about twelve hours apart from one another.

• On the side of Earth that’s facing the Moon, the pull of gravity causes oceans to bulge outward.

• On the other side of the Earth, that’s facing away from the Moon, the Moon’s pull on solid ground causes the oceans to bulge there too.

• Because the Earth rotates on its axis, this bulge is constantly changing location.

• Where the bulge is bigger, it’s high tide. Where the water doesn’t bulge, it’s low tide.

• The Moon’s orbit around Earth also causes tidal changes. Most places get two high tides and two low tides each day.

• These tides are usually spaced about twelve hours apart.

• Spring tides – which give us our highest high tides and lowest low tides – occur only during a new or full Moon.

• A tidal range is the difference in size between a high tide and a low tide.

• Spring tides have the largest daily tidal range, where there is the biggest difference in size between a low tide and a high tide. These occur twice a lunar cycle, at a new Moon and a full Moon.

• Spring tides – highest high tides and lowest low tides.

• Neap tides – which give us our lowest high tides and our highest low tides – occur only during first and third quarter Moons.

• Neap tides have the smallest daily tidal range, where there is the smallest difference in size between a low tide and a high tide. These also occur twice a lunar cycle, at a first quarter and third quarter Moon.

• Neap tides = lowest high tides and highest low tides.