Coastal Processes

Question 1

how do waves form?

Answer 1

by friction with air
- energy from wind is transferred to waves on the surface

Question 2

does the water move in waves?

Answer 2

no
-> only energy transfers

Question 3

in what motion do water particles move?

Answer 3

circular orbits

Question 4

does orbit diameter increase or decrease with distance from the bottom?

Answer 4

increases

Question 5

is there energy loss when waves reflect from objects?

Answer 5

no
-> energy is only transferred not loss

Question 6

crest

Answer 6

highest point of wave

Question 7

trough

Answer 7

lowest point of the wave surface -> not the point deep in the water column only the SURFACE

Question 8

wave length

Answer 8

from crest to crest

Question 9

height

Answer 9

amplitude
- trough to crest

Question 10

period

Answer 10

t - sec
- time of passage of successive crests

Question 11

velocity

Answer 11

L/t for waves in deep water

Question 12

depth

Answer 12

half of L of a wave
L/2

Question 13

does the whole water column move horizontally?

Answer 13

NO
- circular motion at the top

Question 14

what happens with D> L/2?

Answer 14

water motion is negligible

Question 15

what happens in deep water with waves?

Answer 15

in deep water-> wave action diminishes

Question 16

what happens to waves in shallow water?

Answer 16

wave action does not diminish, wave energy reflects off the bottom
-> waves feel the bottom
-> water depth is less than half the length (D < L/2) - wave becomes elliptical and particles are displaced
-> when water gets too high it breaks

Question 17

what happens when H to L ratio is greater than 1/7?

Answer 17

wave is unstable and collapses (breaks)

Question 18

is the wave stable or unstable when heigh is 1/7 the length?

Answer 18

wave is stable

Question 19

what does the surface tension of water allow for?

Answer 19

energy to be captured

Question 20

whats the order of waves?

Answer 20

ripple then swell then waves

Question 21

how is the final wave height determined?

Answer 21

• average velocity of wind
• length of time the wind blows
• fetch - distance over surface which the wind blows

Question 22

what are the two types of wind waves?

Answer 22

• local seas: short period, irregular -> wind driven
• swell: long period, reg, independent of local winds -> driven by distant weather conditions

Question 23

what are rogue waves?

Answer 23

• not wind waves
• usually huge waves without warning
• wave reinforcement -> 2 waves interacts and wave height is added together
• interaction of storms with currents

Question 24

whats an example of rogue waves?

Answer 24

Draupner Oil Perform

Question 25

what are tsunamis?

Answer 25

- harbor wave - not wind waves - caused by undersea earthquakes -> tectonic plates that slide past each other and get caught and cause a break - long wave lengths - loses very little energy - slipping of ocean faults

Question 26

what is an example of a system that measures tsunamis?

Answer 26

- Neptune Canada ->Ocean Networks Canada - pressure on sea floor is equivalent to eave height

Question 27

what drives internal waves?

Answer 27

density driven - occurs where low density water lies over higher density water - propagation of the wave occurs at interface -> wave in-between 2 water bodies - influenced by tides in shallow water -> estuary where fresher water is coming out and saltier water coming in with tide (wedge)

Question 28

what are internal waves?

Answer 28

stratification of the inner water column

Question 29

why is the intermediary water and basin water distinct?

Answer 29

the sill keeps the 2 kinds of water separate and creates internal waves

Question 30

whats an example of famous internal waves?

Answer 30

Tasman Sea -> one of the few that has waves that move in one direction making it easier to study

Question 31

tide types?

Answer 31

dinural - once a day semi-diurnal - twice a day mixed semidiurnal - diff highs and lows during the day

Question 32

what causes tides?

Answer 32

gravitational pull of the sun and moon - pulls the water - types and number dependent on location

Question 33

why is the gravitational effect of the moon stronger than sun?

Answer 33

closer to us - 6x stronger

Question 34

what does the moon's rotation around earth give?

Answer 34

monthly cycles - spring and neap

Question 35

what are spring tides?

Answer 35

2 of them during new or full moon - greatest vertical tidal range, highest high or lowest low

Question 36

what are neap tides?

Answer 36

2 of them during half moon - smallest vertical tidal range - perpendicular to sun so forces do not cooperate

Question 37

what gives daily cycles?

Answer 37

earth's rotation

Question 38

what gives annual cycle?

Answer 38

earth's orbit of sun

Question 39

what are the tide cycles?

Answer 39

daily: 12h25min, 24h50min (1 per day) biweekly: 14 days (27.32 days) half yearly: 6M ( 1yr)

Question 40

what causes the 12h25min cycle?

Answer 40

- gravitational attraction of moon - inertial force of the earth-moon sys - motion of moon in same direction as earth's rotation

Question 41

what causes the 24h50min cycle?

Answer 41

gravitational attraction of moon

Question 42

what causes the monthly cycle?

Answer 42

combo of earth, moon and sun and their alignments

Question 43

what causes the yearly cycle?

Answer 43

earth, moon, sun and maybe the tilt of earth as it moves around the sun diff regions of earth are closer or further from sun

Question 44

what are tide cyc;es?

Answer 44

in diff location are function of basin shape, basin size and latitude

Question 45

what are tidal buldges?

Answer 45

giant incoming waves - more shallow = more noticeable

Question 46

what happens in narrowing channels?

Answer 46

amplified or dampened tides or causes tidal bores and Seiches

Question 47

what affects predicted tides?

Answer 47

coastlines

Question 48

tidal bore

Answer 48

tide moving up a river channel and outflow is overpowered and creates breaker that pushes water forward

Question 49

Seiche

Answer 49

standing wave caused by the wave reflecting off shorelines

Question 50

what factor affects tides?

Answer 50

weather patterns - atmospheric pressure - low pressure cause storm surge or storm tides - Irma