Chapter 10

Question 1

When waves reach shallow water, their velocity is controlled by water

Answer 1

depth

Question 2

As waves approach the seashore,

Answer 2

wave height increases.

Question 3

If you were the captain of a submarine, to what MINIMUM depth would you submerge your vessel in order to avoid the effects of waves with wavelengths of 100 m?

Answer 3

50 m

Question 4

When waves shoal, what occurs?

Answer 4

They eventually break when wave height becomes too high and wavelength becomes too short.
Water particle orbital motions flatten. The distance between 2 successive crests or troughs decreases.
Crests overtake troughs.

Question 5

What is the ultimate effect of wave convergence on headlands and divergence in embayments?

Answer 5

Headlands shrink (erode), and embayments fill in.

Question 6

Tsunami typically have ________ relative to wind-blown waves.

Answer 6

long periods and long wavelengths

Question 7

What is correct about tsunami in the deep ocean?

Answer 7

They are always “feeling” the bottom.

Question 8

The small waves restored by surface tension are called _____________ waves.

Answer 8

capillary

Question 9

Wave height is the vertical distance from the ____ to the _____.

Answer 9

crest, trough

Question 10

Destructive interference occurs as:

Answer 10

the crest of one wave coincides with the trough of an oncoming wave.

Question 11

Which of the following is not one of the factors influencing wave height?

Answer 11

wind direction

Question 12

The maximum possible height of any given wave:

Answer 12

cannot be more than 1/7th the wave length.

Question 13

The main factor influencing the length and speed of shallow water waves is:

Answer 13

water depth

Question 14

true or false: Tsunamis are classified as shallow water waves.

Answer 14

true

Question 15

The wave base:

Answer 15

is the depth below which there is no wave action, is a depth equal to half the wavelength

Question 16

As a wave begins to “touch bottom” near a shoreline:

Answer 16

its height increases and wavelength decreases

Question 17

Waves of a similar period that are sorted out by wavelength are called:

Answer 17

swell

Question 18

Significant wave height refers to:

Answer 18

the mean height of the largest one-third of the waves

Question 20

define internal wave

Answer 20

form at the boundaries of water masses of different
densities (i.e. at a pycnocline), and propagate at depth

Question 21

define tidal wave

Answer 21

due to the movement of the tides.

Question 22

define tsunami waves

Answer 22

large waves created as a result of earthquakes or other
seismic disturbances.

Question 23

define splash waves

Answer 23

form when something falls into the ocean and creates a
splash.

Question 24

define atmospheric waves

Answer 24

form in the sky at the boundary between air masses
of different densities

Question 25

define trough

Answer 25

lowest point

Question 26

define wavelength

Answer 26

distance (m) between two identical points on successive waves (such as crest to crest or trough to trough)

Question 27

define wave steepness

Answer 27

the ratio of wave height to length (H/L); if this ratio exceeds 1/7 (i.e. height exceeds 1/7 of the wavelength) the wave gets too steep, and will break

Question 28

define period

Answer 28

time (s) it takes for a wave to move a distance of one wavelength

Question 29

define frequency

Answer 29

the number of waves passing a point in a given amount of time, usually expressed as waves per second (in hertz; 1 Hz = 1 cycle per second). This is the inverse of the period (f = 1/T). ▪ Speed: how fast the wave travels, or the distance travelled per unit of time. This is also called celerity (C) 𝐶 = 𝐿 𝑇 = 𝐿 × 𝑓 Webb, 2023; Fig. 10.1.2

Question 30

define wave base

Answer 30

depth below which water is unaffected by surface wave action and there is no more circular (orbital) movement (approximately one-half of the wavelength)

Question 31

what are shallow water waves in terms of a formula

Answer 31

water depth ≤ 1/20 𝐿

Question 32

define fetch

Answer 32

(distance over which the wind blows across the water in the same direction)

Question 33

define swell

Answer 33

mature wind waves of one wavelength that form orderly undulations of the ocean surface

Question 34

define wave train

Answer 34

a group of waves of similar wavelength and period moving in the same direction across the ocean surface

Question 35

As waves move into shallow water:

Answer 35

--Speed decreases ▪ Wavelength decreases ▪ Height increases ▪ Steepness increases ▪ Orbital paths flatten, become elliptical ▪ Period remains the same ▪ Waves break → influence of shore slope

Question 36

what causes a tsunami

Answer 36

Large waves created as a result of earthquakes or other seismic disturbances