Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
117 Cards in this Set
- Front
- Back
|
who developed the universal law of gravitation?
|
Newton
|
|
|
wavelengths of tides are measured in...
|
thousands of kilometers
|
|
|
heights of tides are measured in....
|
meters (heights are about 15 m)
|
|
|
the moon and the earth rotate around a common center of mass known as the....
|
barycenter
|
|
|
the barycenter is located ____ km below the earth's surface
|
1600
|
|
|
how is gravitational force related to mass? distance?
|
directly proportional to mass; inversely propotional to the square of the distance
|
|
|
which has the greater effects on tides: the moon or sun?
|
moon
|
|
|
what is the zenith?
|
the point closest to the moon, where the greatest gravitational attraction occurs
|
|
|
what is the nadir?
|
the point farthest from the moon, where the gravitational attraction is the weakest
|
|
|
the froce required to keep planets in their orbits is called....
|
centripetal force
|
|
|
if all gravity in the universe suddenly stopped, the earth would.....
|
the momentum of the earth would send the earth flying off into space along a straight line path, tangent to its orbit around the sun
|
|
|
the difference between the supplied gravitational force and the required centripetal force creates.....
|
a resultant force
|
|
|
how big are resultant forces, compared to earth's gravity?
|
very small, about one millionth the magnitude of earth's gravity
|
|
|
how is the tide generating force related to mass? to distance?
|
directly proportional to mass; inversely proportional to the cube of the distance
|
|
|
how many bulges does the tide generating force create?
|
2; one towards the moon and one away from the moon
|
|
|
are there tides in other objects, such as lakes and swimming pools?
|
yes, but they're really small
|
|
|
True or False: tidal bulges are created when there is a significant horizontal component to the resultant force
|
True
|
|
|
the bulge that points towards the moon is created because....
|
the supplied gravitational force is greater than the required centripetal force
|
|
|
the bulge that points away from the moon is created because...
|
the required centripetal force is greater than the supplied gravitational force
|
|
|
what are 4 underlying assumptions of the equilibrium tide theory?
|
1. earth has 2 equal tidal bulges, one toward the moon and the other away from the moon
2. oceans cover the entire earth and are of a uniform depth 3. there is no friction between ocean water and the sea floor 4. the continents have no influence |
|
|
why can't the equilibrium tide theory (ETT) be used to accurately predict tides at specific locations on earth?
|
it makes assumptions that are not true; it ignores complexities of real tides
|
|
|
according to the ETT, if you were standing on the equator, how many high tides would you experience each day?
|
2
|
|
|
according to the ETT, the tidal period is...
|
12 hours
|
|
|
according to the ETT, if you moved away from the equator to higher latitudes, what would happen to the size of tidal bulges?
|
they would get smaller
|
|
|
in most places on earth, how often do high tides occur?
|
12 hrs and 25 min
|
|
|
how is the lunar day measured?
|
from the time the moon is on the meridian of an observer to the next time the moon is on that meridian
|
|
|
how is the solar day measured?
|
from the time the sun is on the meridian of an observer to the next time the sun is on that meridian
|
|
|
how long is the lunar day? solar day?
|
lunar day = 24 hrs 50 min (28 sec)
solar day = 24 hrs |
|
|
why is a lunar day 50 min longer than a solar day?
|
during the 24 hrs it takes earth to make a full rotation, the moon has continued movin another 12.2 degrees to the east in its orbit around earth, so the earth must rotate an additional 50 min to "catch up" to the moon
|
|
|
the tide generating force by the sun is what precent of the tide genearting force by the moon?
|
46%
|
|
|
how massive is the sun compared to the moon?
|
27million times moon mass
|
|
|
when tides move in towards the shore, they are called....
|
flood tides
|
|
|
when tides move away from the shore, they are called...
|
ebb tides
|
|
|
lunar bulges are ___ the size of solar bulges
|
twice
|
|
|
why does the moon have twice the tide generating force of the sun?
|
the moon is so much closer
|
|
|
when do spring tides and neap tides occur?
|
spring tides at each new moon and full moon and neap tides at each first and third quarter phases of the moon
|
|
|
how does the declination of the moon vary?
|
between 28.5 degrees north and south of the equator
|
|
|
how does the declination of the sun vary?
|
between 23.5 degrees north and south of the equator
|
|
|
when are tidal ranges the greatest?
|
when te earth is nearest the sun and moon
|
|
|
what does the dynamic tide theory (DTT) consider that the ETT leaves out?
|
friction and the true shape of ocean basins
|
|
|
according to the DTT, why can't 2 bulges on opposite sides of earth exist?
|
because they cannot keep up with the rotational speed of earth
|
|
|
what is the amphidromic point and why do we care?
|
a point of zero tidal range; tidal cells rotate around an amphidromic point
|
|
|
tidal rotation is ___ in N hemisphere and ___ in S hemisphere
|
counterclockwise; clockwise
|
|
|
what are 3 types of tidal patterns observed on earth?
|
diurnal, semidiurnal, mixed
|
|
|
what is the most common tidal pattern in the world: semidiurnal, diurnal, or mixed
|
mixed
|
|
|
where does the largest tidal range in the world occur? what is the tidal range?
|
17 m (56 ft) at Bay of Fundy in Nova Scotia
|
|
|
why does the Bay of Fundy have such a large tidal range?
|
because of the effects of constructive interference and the shoaling and narrowing of coastal bays
|
|
|
when does the maximum velocity of reversing currents occur?
|
during flood and ebb currents when the water is halfway between high and low slack waters
|
|
|
why are the tides important to grunions?
|
they time their spawning cycle to match the pattern of the tides
|
|
|
how long is the monthly tidal cycle?
|
29.5 days- the time it takes for the moon to complete an orbit around the earth
|
|
|
when the moon is between earth and the sun it is called...
|
new moon
|
|
|
when the earth is between the moon and the sun, it is called...
|
full moon
|
|
|
when does a quarter moon occur?
|
when the moon is at right angles to the sun relative to earth
|
|
|
when the earth-moon-sun system is aligned, the moon is said to be in....
|
syzygy
|
|
|
constructive interference btwn solar and lunar tidal bulges occur during....
|
new moon and full moon
|
|
|
destructive interference between solar and lunar bulges occur during....
|
first and third quarter moon
|
|
|
what is the time between successive spring tides? neap tides?
|
about 2 weeks; about 2 weeks
|
|
|
the time between a spring tide and successive neap tide is about...
|
one week
|
|
|
as the mooooooooooon progresses from new moon to 1st quarter phase, it is called....
|
waxing crescent
|
|
|
as the moon progresses from 1st quarter to full moon, it is called....
|
waxing gibbous
|
|
|
as the moon progresses from full moon to 3rd quarter, it is called...
|
waning gibbous
|
|
|
as the moon progresses from 3rd quarter to new moon, it is called...
|
waning crescent
|
|
|
what is a blue moon?
|
the second full moon of any calendar month, which occurs when the 29.5 day lunar cycle falls entierly within a 30 or 31 day month
|
|
|
the angular distance of the sun or moon above or below earth's equatorial plane is called...
|
declination
|
|
|
the imaginary plane that contains the ellipse around which earth revolves is called...
|
the ecliptic
|
|
|
what is precession? how long does it take?
|
the rotation of the moon's orbit; 18.6 yrs
|
|
|
how far is the earth away from the sun during N hemisphere summer? winter?
|
summer- 148.5 million km
winter- 152.2 million km |
|
|
tidal ranges are largest when earth is near its closest point to the sun, called....
|
perihelion
|
|
|
tidal ranges are smallest when earth is near its most distant point to the sun, called...
|
apohelion
|
|
|
tidal ranges are largest when earth is near its closest point to the moon, called...
|
perigee
|
|
|
tidal ranges are smallest when earth is near its farthest point to the moon, called...
|
apogee
|
|
|
the earth-moon distance varies between ___ and ___ km
|
375,000 and 406,000
|
|
|
the moon cycles btwn perigee, apogee, and back to apogee every __ days
|
27.5
|
|
|
what is a proxigean tide?
|
when spring tides coincide with perigee
|
|
|
tidal bulges move as ____ waves, with their speed determined only by ____
|
forced (or shallow water); ocean depth
|
|
|
based on the average ocean depth, the average speed at which tide waves can travel acorss the open ocean is about ____ (in km/hr)
|
700 km/hr
|
|
|
what are cotidal lines?
|
they connect points where high tide occurs simultaneously
|
|
|
what limits the size of tidal cells?
|
the wave must complete one rotation during the tidal period (usually 12 lunar hours)
|
|
|
low tide occurs ___ hrs after high tide in an amphidromic cell
|
6
|
|
|
tides are composed of multiple tide waves called.....
|
partial tides
|
|
|
this mathematical approach is useful in studying tides and it takes into account the numerous tide generating variables that possess a periodicity
|
harmonic analysis
|
|
|
describe a diurnal tidal patterN
|
a single high and low tide each lunar day
|
|
|
where are diurnal tides common?
|
in shallow inland seas such as the gulf of mexico and along the coast of SE asia
|
|
|
describe a semidiurnal tide pattern
|
2 high and 2 low tides each lunar day
|
|
|
where are semidiurnal tides common?
|
along the Atlantic coast of US
|
|
|
describe mixed tidal patterns
|
have characteristics of both semidiurnal and diurnal tides
|
|
|
where are mixed tidal patterns common?
|
along the Pacific coast of N American and lots of other places
|
|
|
True or False: Typically, the tidal pattern for a location changes
|
False
|
|
|
what is a tidal bore and how is it produced/
|
a wall of water that moves up certain low lying rivers due to an incoming tide; when an incoming tide rushes up a river, it develops a steep forward slope because the flow of river resists the advance of the tide
|
|
|
True or False: Tidal bores can reach heights of 12 m and travel 47 km/hr
|
False; 5 m, and speeds up to 22 km/hr
|
|
|
True or False: A tidal bore is a true tidal wave
|
True
|
|
|
where do tidal bores develop
|
where there's a large tidal range and a low lying river
|
|
|
True or False: the Amazon River does not have prominent tidal bores
|
False
|
|
|
where are the largest tidal bores in the US found?
|
Cook Inlet near Anchorage, Alaska
|
|
|
Even though the Bay of Fundy has the world's largest tidal range, why doesn't its tidal bore exceed a height of a few meters?
|
because it is so wide
|
|
|
how is the period of a free standing wave determined?
|
by the length and depth of the basin
|
|
|
when do resonance tides occur?
|
when the characteristic period of the free wave is very near that (or a multiple) of the period of a forced wave resulting from tide generating forces, the oscillations may reinforce one another to produce resonance tides
|
|
|
give an example of a lake that displays resonance tides
|
Lake Ontario
|
|
|
a free standing wave is aka a...
|
seiche
|
|
|
where does the maximum tidal range in the Bay of Fundy occur: at its northern end or southern end?
|
northern
|
|
|
in the northern end of Minas basin in the Bay of Fundy, the maximum spring tidal range is....
|
17 m
|
|
|
rotary tidal currents occur in _________________________ whereas reversing tidal currents occur ___________________
|
the deep ocean; close to shore
|
|
|
rotary currents in the open ocean have speeds usually below _______. reversing currents can reach speeds up to _____ in restricted channels
|
1 km/hr; 44 km/hr
|
|
|
when does high slack water occur?
|
at the peak of each high tide
|
|
|
when does low slack water occur?
|
at the peak of each low tide
|
|
|
True or False: Grunion are the only marine fish in the world that completely come out of the water to spawn
|
True
|
|
|
how long are grunion?
|
12-15 cm
|
|
|
how long do grunion live?
|
2-3 yrs, although some 4 yr olds have been recovered
|
|
|
True or False? Strongest gravitational influence = maximum sea water bulge = highest tide.
|
True
|
|
|
What would tides be like on Earth if the Moon did not exist?
|
Tides would occur, but the tidal range would be reduced
|
|
|
A high tide is at 3:00 p.m. on a particular day. On the very next day, a high tide would most likely be expected at...
|
3:50 pm
|
|
|
Under ideal conditions for the west coast U.S., the time interval between a high tide and the next high tide would be
|
12 hours, 25 minutes
|
|
|
Resultant tidal forces are produced by...
|
the difference between centripetal and gravitational forces
|
|
|
The greatest tidal range on Earth occurs during the times when the Moon is at ___________ and the Sun is at __________
|
perigee; perihelion
|
|
|
True or False: During the time of a solar eclipse, neap tide conditions are experienced
|
False
|
|
|
True or False: A tidal bore is a boring, uninteresting wave
|
True
|
|
|
True or False? The best time to go collecting at a tide pool (when there would be the lowest low tides) is during neap tide conditions
|
False
|
