Chapter 10 Flashcards
waves
When waves reach shallow water, their velocity is controlled by water
depth
As waves approach the seashore,
wave height increases.
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?
50 m
When waves shoal, what occurs?
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.
What is the ultimate effect of wave convergence on headlands and divergence in embayments?
Headlands shrink (erode), and embayments fill in.
Tsunami typically have ________ relative to wind-blown waves.
long periods and long wavelengths
What is correct about tsunami in the deep ocean?
They are always “feeling” the bottom.
The small waves restored by surface tension are called _____________ waves.
capillary
Wave height is the vertical distance from the ____ to the _____.
crest, trough
Destructive interference occurs as:
the crest of one wave coincides with the trough of an oncoming wave.
Which of the following is not one of the factors influencing wave height?
wind direction
The maximum possible height of any given wave:
cannot be more than 1/7th the wave length.
The main factor influencing the length and speed of shallow water waves is:
water depth
true or false: Tsunamis are classified as shallow water waves.
true
The wave base:
is the depth below which there is no wave action, is a depth equal to half the wavelength
As a wave begins to “touch bottom” near a shoreline:
its height increases and wavelength decreases
Waves of a similar period that are sorted out by wavelength are called:
swell
Significant wave height refers to:
the mean height of the largest one-third of the waves
define internal wave
form at the boundaries of water masses of different
densities (i.e. at a pycnocline), and propagate at depth
define tidal wave
due to the movement of the tides.
define tsunami waves
large waves created as a result of earthquakes or other
seismic disturbances.
define splash waves
form when something falls into the ocean and creates a
splash.
define atmospheric waves
form in the sky at the boundary between air masses
of different densities
define trough
lowest point
define wavelength
distance (m) between
two identical points on successive waves
(such as crest to crest or trough to trough)
define wave steepness
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
define period
time (s) it takes for a wave to move a distance of one wavelength
define frequency
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
define wave base
depth below which water is
unaffected by surface wave action and there
is no more circular (orbital) movement
(approximately one-half of the wavelength)
what are shallow water waves in terms of a formula
water depth ≤ 1/20 𝐿
define fetch
(distance over which the wind blows across the water in the
same direction)
define swell
mature wind waves of one
wavelength that form orderly undulations
of the ocean surface
define wave train
a group of waves of similar
wavelength and period moving in the same
direction across the ocean surface
As waves move into shallow water:
–Speed decreases
▪ Wavelength decreases
▪ Height increases
▪ Steepness increases
▪ Orbital paths flatten, become elliptical
▪ Period remains the same
▪ Waves break → influence of shore slope
what causes a tsunami
Large waves created as a result of earthquakes or other seismic
disturbances
