Chapter 6 Opener

Figure 6.1 A rock tossed into a calm body of water generates surface gravity waves that propagate outward in all directions

Figure 6.2 Ocean waves can take many forms, as these examples show

Figure 6.3 Capillary waves are very short-wavelength waves that can eventually transition to surface gravity waves

Figure 6.4 A capillary wave on the surface of the ocean provides a face the wind blows against, making for a more efficient transfer of wind energy to the ocean

Figure 6.5 The orbital path, equal to the wave height, traced by a particle of water on the surface of the ocean as a wave passes from left to right

Figure 6.6 The refraction of waves toward beaches and Stokes Drift cause floating debris to accumulate on beaches, rather than being washed out to sea

Figure 6.6 The refraction of waves toward beaches and Stokes Drift cause floating debris to accumulate on beaches, rather than being washed out to sea

Figure 6.7 Wave orbits continue with depth beneath a surface wave, but their diameters quickly diminish

Figure 6.8 In a shallow water wave, the bottom causes the wave orbits to flatten

Figure 6.9 Shapes of swells and seas

Figure 6.10 Stages in the development of a sea

Figure 6.11 Photograph taken from a ship at sea where the sea has become fully developed for that wind speed, which on this day was about 20 knots

Figure 6.12 (A) Plot of the required fetch and duration for there to be a fully developed sea at indicated wind speeds. (B) Wave heights for a fully developed sea at the indicated wind speeds

Figure 6.13 (A) The USS Ramapo observed what is believed to be the largest wave ever recorded. (B) The 112-foot wave occurred in 1933 in the Pacific Ocean

Figure 6.14 (A) Diagram of wave speed and group speed with time. (B) Frames from a video clip, selected at approximately one second intervals, after a rock is tossed into the water

Figure 6.14 (A) Diagram of wave speed and group speed with time

Figure 6.14 (B) Frames from a video clip, selected at approximately one second intervals, after a rock is tossed into the water

Figure 6.15 As a deep water wave approaches shore it will begin to transition to an intermediate and then shallow water wave

Figure 6.15 As a deep water wave approaches shore it will begin to transition to an intermediate and then shallow water wave

Figure 6.16 (A) How two sets of waves of equal wave heights but unequal wavelengths would interfere with one another to produce a wave that is the sum of the two original waves (B)

Figure 6.17 (A) A merchant ship in the Bay of Biscay in heavy seas as a rogue wave looms astern. (B) Photograph taken from the SS Spray in 1986 in the Gulf Stream

Figure 6.18 Sea walls in front of homes on an eroding beach in Southern Maine

Figure 6.19 (A) Waves refract toward the shallower water depths. (B) Viewed from above, waves will diffract around an obstruction. (C) Diffraction and refraction

Figure 6.20 Waves that arrive at an oblique angle on a beach create alongshore current in the swash zone

Figure 6.21 A seiche in a lake

Figure 6.22 (A) The first waves from December 2004 Indian Ocean tsunami coming ashore. (B) Destruction left behind in Banda Aceh, Indonesia, in early January 2005

Figure 6.23 The first ten hours of propagation of the 2004 tsunami across the Indian Ocean; the wave continued to propagate beyond the Indian Ocean and was detected around the world

Figure 6.24 An internal wave propagating along a pycnocline

Figure 6.25 High tide (A) and low tide (B) in the Bay of Fundy, Canada, which has the greatest tidal range in the world, exceeding 15 m (50 feet)

Figure 6.26 (A) The distributions of types of tides around the world: (B) Los Angeles, with a mixed tide; (C) Eastport, Maine, with a semidiurnal tide; and (D) Mobile, Alabama, with a diurnal tide

Figure 6.26 (A) Distributions of the types of tides around the world

Figure 6.26 (B) Los Angeles, with a mixed tide

Figure 6.26 (C) Eastport, Maine, with a semidiurnal tide

Figure 6.26 (D) Mobile, Alabama, with a diurnal tide

Figure 6.27 (A) Imaginary Earth with a single, uniform ocean covering entire surface. (B) Tidal currents that might be expected to result from just the gravitational attraction of the Moon as in (A)

Figure 6.28 The directions of water motions on the surface of the real Earth under the influence of the Moon’s gravitational attraction

Figure 6.29 The reason why there are two tidal bulges on Earth that are attributable to the pull of the moon

Figure 6.30 (A,B) As the Moon orbits around the center of mass of the Earth–Moon pair, Earth orbits around the same point (C) creating a CF equal to but opposite to the g of the Moon

Figure 6.31 The relative importance of the Moon’s gravitational attraction and the Earth’s centrifugal force

Box 6B The Tide-Generating Forces, Figure A

Box 6B The Tide-Generating Forces, Figure B

Box 6B The Tide-Generating Forces, Figure C

Figure 6.32 An idealized Earth rotating beneath an ocean without continents would have two high tides and two low tides

Figure 6.33 (A) Weekly orientations of the Sun, Earth, and Moon orbital system. (B) When they are oriented at right angles, their gravitation forces are perpendicular and there are no additive effects

Figure 6.34 Observed tides recorded at (A) Eastport, Maine, and (B) Boston, Massachusetts, for the month of July 2010

Figure 6.35 (A) A tidal wave entering a bay. (B) Swirling a dishpan of water can make a wave that rotates around the edges of the pan. (C) Hypothetical ocean basin

Figure 6.35 (A) A tidal wave entering a bay

Figure 6.35 (B) Swirling a dishpan of water can make a wave that rotates around the edges of the pan. (C) Hypothetical ocean basin

Figure 6.36 Amphidromic points in the ocean, along with co-tidal phase lines, which approximate the location of the crest of the tidal wave for each hour into the 12 hour lunar tidal cycle

Figure 6.37 (A) Co-tidal phase lines (red), co-range lines (blue); black arrows are counterclockwise movement of the tidal wave crest. (B) Currents in the Gulf of Maine and Bay of Fundy

Figure 6.37 (A) Co-tidal phase lines (red), co-range lines (blue); black arrows are counterclockwise movement of the tidal wave crest

Figure 6.37 (B) Currents in the Gulf of Maine and Bay of Fundy

Figure 6.38 (A) The Gulf of Maine. (B) The resonant frequency of a coffee cup is about 0.2 second. (C) The larger bathtub has a frequency of about 1.5 seconds; this is still quite short

Figure 6.39 Areas of the world ocean where tidal energy is considered sufficient to make tidal power development feasible

Figure 6.40 Diagram of tidal mixing in coastal waters, creating a mixed zone against the coast of cooler waters

Table 6.1