Presentation on theme: "The tide is high…… Where did all this water come from?"— Presentation transcript:
1 The tide is high…… Where did all this water come from?
2 What is a tide? A tide is the: Periodic rise (flood) and fall (ebb) of large bodies of waterThe rise and fall of water to different levels along the shoreline
3 What influences earth’s tides? Tides are influenced by:Gravitational interactions between the Earth, moon, and sunRotation of EarthMoon Cycle
4 Earth’s rotationTidal interactions have slowed Earth’s rotational period.Eventually (billions of years) Earth and Moon will have the same rotational period (27.3 days)The length of the “day” is increasing.Moon’s orbit is growingTherefore, the day is getting longer, Moon looks smaller, and tides are weakening.
5 Moon verses sun!Tides are more influenced by the gravitational effect of the Moon than they are by that of the SunThe Moon’s closeness to us outweighs by far the Sun’s greater sizeEven though the sun is bigger the moon is closer 240,000 miles verses the sun 93 million miles
6 Effects of the sunThe effect of the sun is about half that of the MoonParticularly large tides are experienced when the Earth, moon, and sun line up
7 Moon’s GravityThe moon’s gravitational pull influences the tides even though it is relatively weak.It pull son Earth and its surfaceThe areas closest to the moon are pulled the strongestThe Moon tries to pull on Earth to bring it closer. The Earth is able to hold onto everything but the water.
8 Tidal BUlge Battle of the Bulge Where the ocean is directly facing the moon, the water bulges toward the moon. The water on the opposite side gets “left behind” The bulges are called high tides.
9 “Bathtub effect”The Tidal Bulge occurs similar to as if you were in a bathtub full of water. If you move forward, the water moves backwards, and visa versa – if you move backwards, the water moves forward.
10 High and low tideHow often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth.
11 Tides can rise as much as 40 feet! Two tides occur each dayAbout 12 hours and 25 minutes between two high tides
12 What are spring tides?It has nothing to do with the season or the coiled piece of steel!Comes from the German word springers, which means “to rise up”Tides that produce the greatest difference between high and low tidesOccur twice a month
13 Spring tide Sun, moon, and Earth are all lined up in a row Causes an extreme bulge following the line of the sun and the moonHigh tides are at their highestLow tides are at their lowest
25 What is a tidal bore?The leading edge of the incoming tide forms a wave of water that travels up a river or narrow bay against the direction of the currentFormed when an incoming tide rushes up a riverRiver is flowing in the opposite directionTidal bore develops a steep forward slope due to river’s resistance