Oceano Quiz 9

largest factor that determines gravitational force

distance between the two Masses

Earth's three different tidal patterns

diurnal, semidiurnal, and mixed

Which phase(s) of the moon result in a low tidal range?

first quarter moon third quarter moon

(mixed tidal system) What pattern of tides would you expect to see for a mixed tidal system?

four tides of different heights

Solar Tidal Bulges

half the size of lunar bulges; one underneath the sun and one directly opposite the sun. However, because the sun is so far away, the solar tidal bulges are only about half the size of the lunar tidal bulges. As such, the solar tidal bulges act to mitigate the high and low tides on Earth that are created by the lunar tidal bulges. Essentially, the tidal range (the difference between high and low tide) changes according to the moon's phase, and according to the interference between lunar and solar tides.

The greatest tidal range on Earth occurs during the times when the Moon is at ________ and the Sun is at ________.

perigee; perihelion

In the open ocean, tidal currents follow which of the following patterns?

rotary

Diurnal tidal patterns

show one high tide and one low tide per (lunar) day

Mixed tidal patterns

show two high tides and two low tides of unequal heights during each (lunar) day.

When would the oceans experience the greatest tidal range?

when Earth is in perihelion and the Moon is in perigee

perihelion

-The Earth/moon are closest to the sun at perihelion -When the Earth is closest to the sun (perihelion), around January 2 of the calendar year, tidal ranges are enhanced.

aphelion

-The Earth/moon are furthest away at aphelion -At aphelion, when the Earth is furthest from the sun, around July 2, tidal ranges are reduced.

perigee

-The moon is closest to Earth at perigee -Once a month, at perigee, when the moon is closest to the Earth, tide-generating forces are higher than usual, producing above average ranges in the tides. -

apogee (hint: think 'a' for apart)

-The moon is farthest away from the moon during apogee. -About two weeks later, at apogee, when the moon is farthest from the Earth, the lunar tide-raising force is smaller, and the tidal ranges are less than average.

Neap Tides (smallest tidal range)

A quarter moon is associated with a small tidal range Destructive interference between the solar and lunar tidal bulges occurs

semidiurnal tidal pattern

A semidiurnal tidal pattern has two high and two low tides of approximately equal heights during each lunar day. -the tidal period (the time between high tides) is 12 hours 25 minutes. So, the time from a low to high tide would be half that (6 hours and 12.5 minutes).

Splash" or "Spray" Zone

Above high tide water line; depends on sea spray/mist for water coverage

in the United States

Semidiurnal tides are found on the east coast, diurnal tides are found on the Gulf coast, and mixed tides are found on the west coast. Overall, diurnal tidal patters are more limited, because most places on Earth experience two high and two low tides a day (semidiurnal and mixed semidiurnal tidal patterns). The most common tidal pattern is mixed, since most places on Earth rotate into and out of different parts of each tidal bulge.

What is the difference between perihelion and aphelion?

Perihelion is when Earth is closest to the Sun, and aphelion is when it is farthest from the Sun.

benthic organisms

Plants and animals living in or on the bottom in aquatic environments. Ex:crabs, coral, clams

Why is the idealized highest high tide at 28 degrees south latitude delayed by 12 hours from the highest high tide at 28 degrees north latitude?

That is how long it takes for the location at 28 degrees south latitude to rotate into the largest part of the high tide bulge.

Why does the Moon reach perigee two days before it completes its 29-and-a-half-day lunar cycle?

The Moon's orbit around Earth shifts position over time.

Observed Tides May be Different from Predicted Tides

Tidal charts, like the one above, are based on predicted tides (base on predictable Earth-Moon-Sun relationships.) However, differences can result from: -Onshore winds & low pressure systems, causing higher water levels than predicted; and -Offshore winds & high pressure systems, causing lower water levels than predicted.

aphelion and apogee

Tidal range least at aphelion (July) and apogee; and

tidal period

time that passes between two high tides

Diurnal tides during one tidal period

two tides

tides

very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. Tides originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea surface.

monthly tidal cycle

-29.5 days because that's how long it takes the moon to complete an orbit around the Earth. As mentioned earlier, the moon revolves around the Earth in the same direction that the Earth rotates on its axis (counterclockwise).

Which of the following statements is/are true regarding the lunar day and the solar day?

-A lunar day is the time it takes for a location on Earth that is directly underneath the Moon to make one rotation and reach the same location directly underneath the Moon. -Earth's rotation on its axis is why we experience day and night. It takes 50 minutes for a given location on -Earth to "catch up" to the Moon.

Tidal Patterns

-A mixed tidal pattern has two high and two low tides of unequal heights during each lunar day. -A diurnal tidal pattern has one high and one low tide during each lunar day. -A semidiurnal tidal pattern has two high and two low tides of approximately equal heights during each lunar day.

Which of the following statements is/are true regarding neap tides?

-High tides are low. -Neap tides occur when there is a small tidal range. -Neap tides occur during first quarter moon and third quarter moon.

Rocky Shores

-Most life on the ocean floor depends on the productivity of surface waters, so great abundances of benthic life are found beneath areas of high primary productivity. -Intertidal zones along coastlines occur between the high tide and low tide shoreline. -On rocky shores, pools of water are left behind when the tide retreats, providing a unique ecosystem for marine organisms. -Sediment-covered shores also support a great abundance of life, but they won't have tidepools and are therefore not discussed here.

Neap Tides

-Neap tides occur when the moon is at a 90o angle to the sun, at first-quarter moon and at third-quarter moon. This is when the solar tides and the lunar tides counteract each other, creating a destructive interference. This creates a smaller tidal range on Earth, with the lowest high tides and the highest low tides. Since this configuration occurs at first-quarter and third-quarter moon, it occurs twice a month, or about every two weeks -The name "neap" tides comes from the word "nipped" which refers to the smaller tidal range.

Benthic Biomass

-Of the approximately 230,000 known species in the ocean, more than 98% live in or on the ocean floor. These are called benthic organisms -Hopefully you noticed that the ocean's lowest biomass is beneath the centers of subtropical gyres (in the middle of each ocean basin) and the highest values are in the middle and high-latitude continental shelf areas. -The similarity in the distribution of benthic biomass to that of surface chlorophyll suggests that most of the benthic community receives its food from surface waters.In fact, 99.9% of all marine life depends directly or indirectly on photosynthesis.

(Spring Tides) Which of the following statements is/are true concerning spring tides?

-Spring tides occur when the Earth, Moon, and Sun are aligned. -Spring tides have high high tides.

Two Tidal Bulges

-The two tidal bulges create water levels that are higher than average sea level (high tide), and the places on Earth where water levels are lower than average sea level (low tide). As Earth rotates inside the two tidal bulges, alternating high and low tide are experienced. -One bulge is centered on the Zenith. This bulge is caused by the gravitational pull of the moon on Earth's water. The second bulge is directly opposite the first, and it is centered on the Nadir. Here, the gravitational force pulling the ocean toward moon is weaker and centripetal force is stronger. The rotation of the Earth-moon system causes the ocean to bulge outward.

perigee and perihelion

-Tidal range greatest at perihelion (January) and perigee -Extreme spring tides occur if the moon and sun are over the same latitude and at perigee and perihelion.

Lunar Tidal Bulges

-both sides of the earth bulge in response to the moons gravitational pull (one underneath the moon (centered at Zenith) and one directly opposite the moon (centered at Nadir). -It is high tide when the Earth passes through a lunar tidal bulge, and low tide when the Earth passes out of the bulge. The size of the bulges vary over the course of the month (and year)

(Low tidal range) Which phase(s) of the moon result in a low tidal range?

-first quarter moon -third quarter moon

Tides are

-gravitational forces from the moon and solar energy -one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores.

two high tides and two low tides

-most places on Earth have two high tides and two low tides a day as Earth rotates beneath the two bulges. -Because the Earth rotates through two tidal "bulges" every lunar day, most coastal areas experience two high and two low tides every 24 hours and 50 minutes. High tides occur 12 hours and 25 minutes apart. It takes six hours and 12.5 minutes for the water at the shore to go from high to low, or from low to high.

In one solar day, how far does the Moon move around the Earth?

1/28th of a complete revolution

High Tide Zone

10% beneath water: covered by most high tides but exposed to the air for most of the day

Under ideal conditions for the West Coast of the United States, the time interval between a high tide and the very next high tide would be __________.

12 hours, 25 minutes

If today high tide is at 1:00 p.m., what time will the same high tide be tomorrow?

1:50 p.m

How many spring and neap tides will a tide-recording station experience in a given month?

2 spring tides and 2 neap tides

length of a lunar day

24 hours and 50 minutes

Solar day

24 hours; the time that it takes for a specific site on the Earth to rotate from an exact point under the sun to the same point under the sun.

In a semidiurnal tidal pattern, if a low tide occurs at 9:00 am, approximately when would the next high tide occur?

3:12 pm

In a diurnal tidal pattern, if a high tide occurs at 3:00 pm, approximately when would the next high tide occur?

3:50 pm, the next day

Middle Intertidal Zone

50% beneath water: subjected to multiple emergence and submergence events

Low Tidal Zone:

90% submerged, subjected to high wave energy most of the time

diurnal tidal

A diurnal tidal pattern has one high and one low tide during each lunar day. -For a diurnal tidal pattern, the tidal period (the time between high tides) is 24 hours 50 minutes.

tidal bore

A high, often breaking wave generated by a tide crest that advances rapidly up an estuary or river. a true tidal wave caused by an incoming high tide that moves up certain rivers

mixed tidal pattern

A mixed tidal pattern has two high and two low tides of unequal heights during each lunar day.

Bay of Fundy in Nova Scotia.

At the mouth of the bay, the maximum spring tidal range is 6.6 feet. However, at the northern end of the bay, the restricted opening funnels the water in such a way that this region experiences the largest tidal range in the world (56 feet during spring tides).

Newton's Law of Universal Gravitation

F = Gm1m2/r2

semidiurnal tides during one tidal period

Four

Southern California Tidal Pattern

In Southern California, we experience a mixed (or mixed semidiurnal) tidal pattern. This means that we have two high tides and two low tides a day, with a variable tidal range.

Why are the idealized high tides at the equator all about the same height?

Locations at the equator pass through the same part of the two tidal bulges with each high tide.

What Communities Exist Along Rocky Shores?

Most life on the ocean floor depends on the productivity of surface waters, so great abundances of benthic life are found beneath areas of high primary productivity. Intertidal zones along coastlines occur between the high tide and low tide shoreline. On rocky shores, pools of water are left behind when the tide retreats, providing a unique ecosystem for marine organisms. Sediment-covered shores also support a great abundance of life, but they won't have tidepools and are therefore not discussed here.

tidal ranges unequal most places on Earth

Most of the year, the moon is not centered above equator. As a result, the two tidal bulges are not directly overhead the equator. As shown in the figure below, the two tidal bulges are offset 28.5o north and south of the equator. This is due to the declination of the moon's orbit around the Earth. Declination is the angular distance of the sun or moon above or below Earth's equatorial plane. because the two tidal bulges are not centered on the equator, the heights of the tides vary as the Earth rotates into different parts of each bulge. For this reason, the tidal ranges are unequal on most places on Earth.

Rocky Intertidal Zone

Organisms in the rocky intertidal zone are specifically adapted to the changing conditions and stresses that exist with the changing tides along rocky shorelines. Organisms inhabit a zone that is limited by abiotic factors (such as desiccation, temperature stress, salinity, and wave exposure) and biological factors (including predation and competition). It turns out that finding space is the largest limiting factor!

centripetal force

The centripetal force is the same everywhere on Earth

centripetal force

The centripetal force is the same everywhere on Earth.

Time Interval between tides

The lunar day is 24 hours and 50 minutes. The tidal period is half that, so the next high tide would be 12 hours and 25 minutes later.

first-quarter moon

The moon is a quarter of the way around the Earth. You can see the right half of the moon. the moon and the sun are at ninety degree angles relative to each other (when viewed from Earth).

elliptical orbits

The oval-like path on which an object in space travels.

third-quarter moon

The phase of the moon when it is three-quarters of the way through its orbit, and we see half of the moon lighted At third-quarter moon, the moon and the sun are again at ninety degree angles relative to each other (when viewed from Earth).

semidiurnal period related to a tidal day?

The semidiurnal period is half as long as a tidal day.

At 28 degrees north latitude, why are some idealized high tides higher and some high tides lower?

The tidal bulges are rarely centered on the equator, so this location passes through different parts of the two tidal bulges.

Tide-Generating Forces

The tides are caused by a combination of the gravitational attraction between the earth, the moon, and the sun, the centripetal forces between them, and the motion of the earth-moon system around the sun.

why is the idealized high tide at 28 degrees north latitude higher than the corresponding high tide at 28 degrees south latitude?

These two locations are passing through different parts of the same tidal bulge at the same time.

Ebb Current

Water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches/tide change

tidal range

When the highest part, or crest of the wave, reaches a particular location, high tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high tide and the low tide is called the tidal range.

new moon.

When the moon is between the Earth and the sun, it is called new moon. The moon is not visible from Earth because none of the moon's sunlit face is facing the Earth.

full moon

When the moon is on the side of the Earth opposite the sun, it is called full moon. We see the whole moon, because the illuminated part of the moon is facing Earth.

zenith

Where Earth's gravitational attraction toward the Moon the greatest

Syzygy

a conjunction or opposition, especially of the moon with the sun -Occurs when the earth-moon-sun system is aligned during spring tides

Lunar Day

a lunar day is the time it takes for a specific site on the Earth to rotate from an exact point under the moon to the same point under the moon. Unlike a solar day, however, a lunar day is 24 hours and 50 minutes. The lunar day is 50 minutes longer than a solar day because the moon revolves around the Earth in the same direction that the Earth rotates around its axis. So, it takes the Earth an extra 50 minutes to "catch up" to the moon.

Spring Tides

a tide just after a new or full moon, when there is the greatest difference between high and low water. spring tides occur at new moon (when the moon is located between Earth and the sun) and at full moon (when the moon is located on side of Earth furthest from the sun). This is when the solar tides and the lunar tides align in the same direction, creating a constructive interference. This creates a larger tidal range on Earth, with the highest high tides and the lowest low tides. Since this configuration occurs at new and full moon, it occurs twice a month, or about every two weeks. -Note that spring tides don't only occur in the spring season. This name comes from the observation that the tide "springs forth" during these times.

Gravitational Force

an attractive force that acts between any two masses; Newton's law of universal gravitation (Fg = Gm1m2/r2) states that the gravitational attraction between two bodies (Fg) is directly proportional to their masses (m1 and m2), and inversely proportional to the square of the distance between the bodies (r). Therefore, the greater the mass of the objects and the closer they are to each other, the greater the gravitational attraction between them. Because "r" is squared in the equation, the gravitational attraction between two bodies greatly decreases with increasing distance between them.

tidal bulge(s) located

at the nadir and at the zenith

Why is the length of a lunar day different from the length of a solar day?

because the Moon revolves around Earth in the same direction that Earth is rotating on its axis

Zenith and Nadir

strength of the gravitational force is greatest at Zenith and least at Nadir, and the direction points towards the moon's center of mass, so the direction varies depending on where you are on Earth. The strength of centripetal force is the same all over Earth, and the direction is the same all over Earth, towards the moon. At the North Pole, the resultant force points directly south. At the South Pole, the resultant force points directly North. At Zenith, the resultant force points directly towards the moon. At Nadir, the resultant force points directly away from the moon. Points in between are the average.

coastal tidal range

the difference in sea level between a successive high and low tide

What causes variation in Earth's tides over time?

the elliptical orbits of the Moon around Earth, and Earth around the Sun

tides

the regular daily rises and falls in sea level caused by the gravitational attraction of the Moon and Sun on Earth

Semidiurnal

tidal patterns (middle chart) show two high tides and two low tides of approximately equal height per (lunar) day