Tides

What factor is most important in the tide--generating force? Why?

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Where are semidiurnal, diurnal, and mixed tides most likely to occur in equilibrium tidal theory?

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Why is the solar day 50 minutes shorter than the lunar day? Or put another way, why is high tide approximately 50 minutes later each day?

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What is a tide?

A tide is the periodic rise and fall of a body of water due to gravitational interactions between the sun, moon and Earth

What is an amphidromic point?

An amphidromic point is a point of zero amplitude of one harmonic constituent of the tide. The tidal range (the peak-to-peak amplitude, or height difference between high tide and low tide) for that harmonic constituent increases with distance from this point. These points are sometimes called tidal nodes

What are the assumptions associated with dynamic tidal theory?

Assume: • Earth is partially land and partially water covered • Ocean depth varies (wide and shallow) • There is friction between ocean water and seafloor

What is a diurnal tide?

Diurnal tide cycle (upper left). An area has a diurnal tidal cycle if it experiences one high and one low tide every lunar day. Many areas in the Gulf of Mexico experience these types of tides. Period- 24:50

What factors impact gravitational attraction?

Gravity is the main factor affecting tides. The moon's gravity pulls at the Earth, which is able to hold onto everything except for water. Large bodies of water are then drawn to the moon through its gravitational pull, rising and lowering depending on where the moon is closest to the Earth. The sun's gravity also comes into play. During new and full moons, the sun lines up with the moon and the Earth to create very strong spring tides, which are higher and lower than other tides. During the quarter phases, when the three bodies are not lined up, weaker neap tides occur.

What are the characteristics of microtidal, mesotidal and macrotidal settings?

Microtidal: 0-2 m Mesotidal: 2-4 m Macrotidal: > 4 m

What is a mixed tide?

Mixed Semidiurnal tide cycle (lower middle). An area has a mixed semidiurnal tidal cycle if it experiences two high and two low tides of different size every lunar day. Many areas on the western coast of North America experience these tidal cycles. Period- 12:25

What is a semidiurnal tide?

Semidiurnal tide cycle (upper right). An area has a semidiurnal tidal cycle if it experiences two high and two low tides of approximately equal size every lunar day. Many areas on the eastern coast of North America experience these tidal cycles. Period- 12:25

What are spring and neap tides? When are they likely to occur each month?

Spring Tides When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide. Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon. Neap Tides During the moon's quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide. Neap tides are especially weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.

What is the barycenter?

The balance point where the earth and moon rotate around, located 1600 km (1000 m) beneath earth's surface.

Where do the largest tides occur?

The highest tides in the world can be found in Canada at the Bay of Fundy, which separates New Brunswick from Nova Scotia.

What is the tidal range?

The tidal range is the vertical difference between the high tide and the succeeding low tide. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

What are the directions of rotation of amphidromic tides in the southern versus northern hemisphere?

You can see in the picture below where those amphidromic points are found, and how tides rotate around them periodically (anticlockwise in the northern hemisphere, clockwise in the southern one).

What are cotidal and corange lines?

cotidal line- a line on a map connecting points at which a tidal level, especially high tide, occurs simultaneously. corange line- A line on a tidal chart joining places that have the same tidal range or amplitude; usually drawn for a particular tidal constituent or tidal condition (e.g., mean spring tides).

What are the assumptions in equilibrium tidal theory?

• water-covered body • uniform ocean depth • tides only affected by TGF • no friction between water and sediment surface