February 27th and March 1st lecture

Question 1

What are tides?

Answer 1

long period waves

Question 2

What are high tides associated with in a wavelength?

Answer 2

The crest

Question 3

What are low tides associated with in a wavelength?

Answer 3

The trouh

Question 4

can currents also be assosated with tidal processes?

Answer 4

Yes

Question 5

What are incoming currents associated with?

Answer 5

Rising tides, they are called flood currents

Question 6

What are outgoing currents associated with?

Answer 6

Decreasing tides, these are called ebb currents

Question 7

How fast can tidal currents be in coastal waters?

Answer 7

up to 5m/s

Question 8

What cases bottom sediments to be suspended?

Answer 8

Tidal currents

Question 9

Why are tides important?

Answer 9

• Slowly changes earth rotation and length of a day
• causes the moon to slowly move away from the earth
• Keeps the same face of the moon always facing the earth.

Question 10

How do the tides affect the earth and moon ( angular momentum )

Answer 10

Oceanic tides lag behind the tide-generating potential and thus produces forces that transfer angular momentum between the Earth and the Moon

Question 11

True/false: can tides influence the orbits of satellites?

Answer 11

True:

Tides influence the orbits of satellites

Question 12

What is the main causes of tides?

Answer 12

Gravity is the main force that generates tides.

Question 13

What does Newtons Theory of Gravitational Attraction state about the gravitational attraction between two bodies?

Answer 13

• it is directly proportionally to their masses

- it is inversely proportional to the square of the distance between the two bodies.

Question 14

What are tidal forces based off of?

Answer 14

The gravitational attractive force, but varies inversely as the cube of the distance between objects.

Question 15

What is the equation for the tide generating force?

Answer 15

TGF ( inversely proportional to ) Mass/Distance^3

Question 16

Now, if the sun if 27 million times more
massive than the Moon and is 390 times
farther away from the Earth, the ratio of its
tide generating force to that of the moon is

Answer 16

27 million / (390)63 = 0.46

Question 17

How are tidal bulges created? ( three things )

Answer 17

• Gravitation attraction strongest on side facing the moon
• causes water on near side to be pulled towards the moon
• Inertial forces try to keep the water in place, but the gravitational force is larger and a budge appears facing the moon?

Question 18

Why is there two tidal bulges?

Answer 18

• On the opposite side of the earth, Gravitational attraction is weaker.
• Hence inertial forces ( centrigufal )exceed the gravitational force
• Thus the water moves away from the moon, forming another tidal bulge

Question 19

How many tidal bulges do we have?

Answer 19

Two

Question 20

Do the tidal bulges move?

Answer 20

no they do not, they stay in line with the moon, as the earth moves

Question 21

Does anything other than the moon affect tidal bulges?

Answer 21

Interaction with the
sun modifies the tidal
bulges

Question 22

What is lunar declination?

Answer 22

As the moon revolves around the Earth, its angle increases and decreases in relation to the equator

Question 23

how does lunar declination affect the tides?

Answer 23

The two tidal bulges track
the changes in lunar
declination, also increasing
or decreasing their angles to
the equator

Question 24

What is a Solar day?

Answer 24

Time for a specific point on the earth to rotate from
an exact point under the sun back to that same exact point (24
hours)

Question 25

What is a lunar day?

Answer 25

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 – 24 hours and 50 minutes long

Question 26

How many bulges does earth pass through each lunar day?

Answer 26

Two, meaning that there is 2 high tides and 2 low tides

Question 27

Where does the a lunar day take 50min longer than a solar day?

Answer 27

Extra length is because moon revolves around the earth in the same direction as the earth rotates around its axis, needing the extra 50 minutes to “catch up”

Question 28

Does the sun exert a tidal force?

Answer 28

Although not as big as the moons, it still exerts a significant tidal force?

Question 29

What happens to the tidal bulges when the sun and moon are aliened?

Answer 29

the solar bulge has an additive effect on the lunar bulge, creating extra high and very low tides

Question 30

What is the tide called when the sun and the moon are aliened.

Answer 30

Spring tides

Question 31

What happens to the tidal bulge when the sun and the moon are at right angels to one another?

Answer 31

their bulges partially cancel out, producing more moderate tides

Question 32

What is the tide called when the sun and the moon are right angels to one another?

Answer 32

Neap tides

Question 33

How often do spring and neap tides happen?

Answer 33

Alternatively around every 7 days

Question 34

The Earth has an elliptical | orbit, being closest to the sun in N.H. winter. what happens to the tide at this point?

Answer 34

Tidal ranges are thus largest in January (smallest distance)

Question 35

The moons orbit is also not perfect, with an 87 variance in distance, what happens to the tides as the moon gets closer or farther?

Answer 35

producing changes in tidal amplitude (including strong spring tides and weaker neap tides)

Question 36

Due to the bulges being offset because of the variations in the moon declination, how can it affect tides?

Answer 36

– An island can pass through the bulge on one side of the Earth but miss it on the other – Thus not all locations get two high tides and two low tides of the same amplitude each lunar day

Question 37

What is a Diurnal tide?

Answer 37

: Have one high tide and one low | tide each tidal day.

Question 38

What is a semi-diurnal tide?

Answer 38

Have 2 high and 2 low tides | each tidal day, with the highs and lows having the same height

Question 39

What are mixed tides?

Answer 39

Have 2 high tides and 2 low tides each day – But the heights of the 2 high tides and/or the 2 low tides are different

Question 40

What else affects tides?

Answer 40

The shape of the shoreline can strong affect the tides

Question 41

What can wide continental margins do to tides?

Answer 41

They can lead to increased tide amplitudes

Question 42

What kind of tides do mid-oceanic islands experience?

Answer 42

small tides

Question 43

What kind o tides do funnel shaped days experience?

Answer 43

Funnel-shaped bays in particular can dramatically alter tidal magnitude

Question 44

Can wind and weather affect tides?

Answer 44

Yes, local wind and weather can affect tides on a small scale.