Tides The rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Bay of Fundy at high tide Bay of Fundy at low tide https://www.youtube.com/watch?v=OP0cpXpw8yk https://www.youtube.com/watch?v=EnDJ6_XpGfo

Tidal Cycle A tide is a repeated cycle of sea level changes in the following stages: 1st step Over several hours the water rises or advances up a beach in the flood tide.

Tidal Cycle A tide is a repeated cycle of sea level changes in the following stages: 2nd step Water reaches its highest level, stops at high water. Tidal currents cease. Called slack water or slack tide. Tide reverses direction and is said to be turning.

Tidal Cycle A tide is a repeated cycle of sea level changes in the following stages: 3rd Step The sea level lowers or falls over several hours during the ebb tide.

Tidal Cycle A tide is a repeated cycle of sea level changes in the following stages: 4th Step The level stops falling at low water. This point is also described as slack tide or turning.

A tide is a repeated cycle of A tide is a repeated cycle of Tidal Cycle A tide is a repeated cycle of sea level changes A tide is a repeated cycle of sea level changes

Tides As the Earth rotates, the moon’s gravity pulls water toward the point on the Earth’s surface closest to the moon.

Spring Tides During new moon and full moon, the sun, moon, and Earth are in alignment. The combined gravity causes higher than normal high tides and lower than normal low tides

1st and 3rd quarter moon is at right angles to sun and Earth. Neap Tides 1st and 3rd quarter moon is at right angles to sun and Earth. The sun’s pull is at right angle to the Earth, causing lowest height difference between tides

1st Quarter Moon 3rd Quarter Moon

Use the Force, Luke.. Tidal force - secondary effect of the force of gravity, responsible for the tides. It occurs because the gravitational force exerted on one body by a second body is not constant across its diameter. The side nearest to the second body experiences a greater force, while the opposite side experiences a lesser force. http://www.gly.uga.edu/railsback/Tides/TideHammer01.html http://www.pbs.org/wgbh/nova/venice/tides.html

Once a day Diurnal Tides - In parts of the northern Gulf of Mexico and Southeast Asia, tides have one high and one low water per tidal day

Twice a day Semi-diurnal tides - two high and two low waters per tidal day. They are common on the Atlantic coasts of the United States and Europe.

Can’t Decide! Mixed tides - where successive high-water and low-water levels change a great deal. In these tides, we have a higher high water and lower high water as well as higher low water and lower low water. The tides around west coast of Canada and the United States are of this type.

Where on Earth?

Graphing Tides

To calculate a tidal range, subtract the low tide from the high tide. Minimum Tidal Range = 4.7 feet – 0.6 feet = 4.1 feet 4.7 feet 0.6 feet The tidal range shown above is the minimum tidal range for this time period. What is the name given to tides such as these? What phases of the moon cause these tides?

To calculate a tidal range, subtract the low tide from the high tide. 6.1 feet - 1.1 feet Maximum Tidal Range = 6.1 feet – (-1.1 foot) = 7.2 feet The tidal range shown above is the maximum tidal range for this time period. What is the name given to tides such as these? What phases of the moon cause these tides?

Height (meters) above mean sea level Day Time Height (meters) above mean sea level Monday 6:00 AM 1.5   2:00 PM 6.7 10:30 PM 1.7 Tuesday 7:30 AM 6.5 5:00 PM 1.9 Wednesday 3:00 AM 6.3 1:30 PM 2.1 Thursday 12:30 AM 6.1 12:30 PM 2.3 12:00 AM 5.9 When do we dock? One example of the importance of tides Channel = 15 meters Dockside depth = 15 meters Draft of ship = 12.5 meters

Wave characteristics Wavelength (L): distance between crests Wave Height (H) : vertical distance between crest and trough Wave Period (T): time for successive waves to pass a fixed point

Kiawah Island

Ebb-Tidal Delta

Morris Island Lighthouse Coast Guard Station