Waves and Tides

16.2

Wave Height• The very top of the wave is the crest and the

water that separates the waves is called the troughs.

• The vertical distance between trough and crest is called the wave height.

Wavelength• The horizontal distance between two

successive crests or two successive troughs is called wavelength.

Wave Period• The time that it takes one full wave—one

wavelength—to pass a fixed position is the wave period.

Fetch• Fetch is the distance

that the wind has traveled across open water.

• The energy of the wind is transferred to the water and it increases both the height and steepness of the waves.

Tides• Tides are regular

changes in the elevation of the ocean surface.

• They are the rhythmic rise and fall along the coastline.

Tidal Range• The tidal range is the difference in height

between successive high and low tides. • When the gravity of the sun and the moon

are combined that produces a large tidal range.

Spring tides• Spring tides are the tides that have the

greatest tidal range due to the alignment of the Earth—moon—sun system.

Neap Tides• The sun and the moon partially offset the

influence of the other and as a result, the daily tidal range is less.

• Each month there are two neap tides and two spring tides, each about one week apart.

Where do Ocean waves obtain their energy?

• Most ocean waves obtain their energy from the wind.

• The greater the wind speeds the larger the waves.

Three factors that affect the characteristics of a wave

• The height, length and period that are eventually achieved by a wave depend on three factors…

• 1-wind speed• 2-length of time the wind has blown• 3-fetch

How does energy move through a wave?

• Circular orbital motion allows energy to move forward through the water while the individual water particles that transmit the water to move around in a circle.

• This movement results in a circle that returns an object to the same place in the water.

What causes tides?• Ocean tides result from differences in the

gravitational influence upon different parts of earths surface by the sun, but much more by the moon.