Chapter IIIWaves and Tides

Wave Parts•Waves are driven by wind•Crest•Trough•Size = wave height = vertical

distance between trough and crest•Distance between waves

(wavelength) = period = time it takes the wave to go by a point

Wave Movement•Water particles don’t have any net

movement•Crest move up and forward•Trough move down and back•Carries energy

Formation of Waves

• Wind forms waves

• Fetch = span of open water over which the wind blows

• Swells form in open ocean

• Cancellation = crest and trough meet and average out

• Reinforcement = crest and crest meet and produce a bigger wave

Breaking Waves•In shallow water waves:

•Slow down•Get higher•Get closer together•Break when get too steep and

unstable

Tides• Tides = rhythmic

rising and falling of water caused by the gravitational pull of the sun and moon• Moon has a

stronger pull because it is closer

Gravitational Pull• Moon pulls water towards it

• Bulge on that side of earth• Bulge on opposite side of earth because

of centrifugal force• Earth rotates under the bulge to get high

and low tides• Sun does the same thing, but weaker

• Can have additive impacts

Timing of the tides

•2 high tides, 2 low tides every 24 hrs and 50 min•50 min accounts for the moon’s

movement

Tidal Range• Tidal Range = difference in water level between successive high and low tides• Spring tide = large (sun and moon in

line)• Neap tide = small (sun and moon at

odds)

Tide Types• Number of tides

• Semidiurnal tides = 2 high, 2 low (N. America, Europe, Africa)

• Mixed semidiurnal tides = 2 high, 2 low but of different ranges (West coast of N. America)

• Diurnal tides = 1 high, 1 low (Antarctica, Caribbean, Canada

Tide Types

Tide Tables

•freetidetables.com