Quiz 1: Chapter 11
What is (1) MHHW, (2) MHW, (3) MSL, or MTL, (4) MLW, and (5) MLLW?
(1) MHHW: Mean Higher High Water (2) MHW: Mean High Water (3) MSL, or MTL: Mean Sea Level (4) MLW: Mean Low Water (5) MLLW: Mean Lower Low Water
***What do the (1) perihelion and aphelion, and (2) perigee and apogee, have to do with tides?3
1. Perihelion happens in January where the earth is nearest to the sun. Aphelion is when the earth is furthest from the sun in July Perigee is when the is closest to the earth. Apogee is when the moon is most distant from the earth. The different positions cause different strengths of forces on the tides and tidal ranges with the high and low elevations.
***What is meant by (1) semi-diurnal tides, (2) unequal semi-diurnal tides, (3) diurnal tides, and (4) mixed tides?
1. Semi-diurnal tides happen when there are two cycles in a 24 hour period. 2. An unequal semi-diurnal tide occurs when the elevation during high and low tide differ. 3. A diurnal tide is when there is only one low and one high tide a day 4. Mixed tides are when semi-diurnal and diurnal tides occur
8. What are typical periods for (1) lunar tides, and (2) solar tides?
A typical period for lunar tides last 12 hours and 25 minutes caused by the moon generating force. The solar tides create half of the moons force of 46%. The solar tide is about 12 hours and has its own bulges.
*** What are typical values for (1) tidal wavelengths, (2) tidal amplitudes on open coasts away from inlets and embayments?
For deep waters the typical height is around .5 meters and a wavelength of 10,000km away from tidal inlets
In tidal forcing, what situation is described by (1) syzygy, and (2) quadratic?
In tidal forcing, syzygy occurs when there is an alignment between the Earth, sun, and moon. A quadratic position happens when the moon creates a right angle with the sun and the earth.
For tidal forcing in the gravitational equation, what are (1) m1 and m2, and (2) what is r2?
M1 and M2 are the masses of two separate objects in the gravitational equation. R^2 is the distance between m1 and m2 squared.
What is a "maelstrom"?
Maelstroms are powerful whirlpools in the ocean
Most navigational charts reference water depths to what level?
Most navigational charts reference water depths to the MLLW sea level
6. What are spring and neap tides?
Spring tides are tides that are extremely high and low caused by two bulges. They are characterized by maximum total range. Neap tides occur when there are high low tides and low high tides. These tides are characterized by minimal tidal range.
What is a (1) amphidromic point, (2) co-tidal line, (3) co-range line?
The amphidromic point is the center of the tidal wave that rotates around level. A co-tidal line is the area connecting opposite tides that both occur at the same time. Co-range line links tides that have the same ranges.
***How large are tidal amplitudes in the Bay of Fundy?
The tidal amplitude in the bay of fundi are 12 meters tall
What are the two driving forces for tides?
The two driving forces for tides are the gravitational attraction and the centrifugal forces between the sun, moon, and the earth
Why are there (generally, or most commonly) two high tides and two low tides each day?
There are two high tides and two low tides each day because of the two tidal bulges in which earth rotates under causing a tidal change every 6 hours.
Where are tidal currents important?
Tidal currents are important along coastlines due to the energy source it gives.
How are tides important to shoreline processes on open coast beaches?
Tides are important to shoreline processes on open coast beaches because they create tidal inlets and harbors on coasts world wide. For example, the shoreline on the east coast is shaped by the tides.