Chapters 10

A Wave is a disturbance that carries energy through matter or space.

In oceans, waves move through seawater.

Waves are the movement of energy, not matter.

Crest – highest point of a waveTrough – lowest point of a waveWave Height – vertical distance between the crest and the trough

Wavelength – horizontal distance between two crests or two troughs

Wavelength

Wave Height

Crest

Trough

Still Water

Wave Parts

When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward.

Long waves are called swells Short waves are called chop

Disturbing force Extent of disturbing force Resting force wavelength

Disturbing force◦ Energy that causes waves

Wind, volcanic eruptions, landslides, etc.

Free waves vs. forces waves◦ Free waves form and propagate without further

influence◦ Forces waves are maintained by a disturbing

force

Restoring force◦ Dominant force that that returns the water

surface to flatness

Deep water waves◦ Waves moving through water deeper than half

their wavelength

Shallow water waves◦ Waves in water shallower than 1/20 their original

wavelength Transitional waves

◦ Waves travel through water deeper than 1/20 their original wavelength but shallower than half their original wavelength

Caused by:WindEarthquakesGravitational force of the Moon and Sun.

When wind blows across a body of water, friction causes the water to move along with the wind.

Wave Height depends on – ◦Wind speed◦Fetch: Distance over which the wind blows

◦Duration: Length of time the wind blows

Swell- process of dispersion (wave separation) produces smooth undulation of ocean surface

Wave trains – progressing groups of swell with the same origin

Fully developed sea◦ Strong wind for over 3 days

Largest waves◦ 1480 feet, Iceland◦ 1913, Cape of Good Hope◦ 2720, equatorial Atlantic

Wave video

Higher than the theoretical maximum

When a wave breaks against the shore, the crest outruns the trough and the crest collapses.

Called a breaker.In this case, water does move forward and backward.

Abrupt bulge of water driven ashore by tropical cyclone or frontal storm

Storm surge video

Rocking of a shallow water wave Form of a standing wave that oscillates

vertically with no forward movement

Tsunamis were once called Tidal waves, but they have nothing to do with the tides.

They are produced by earthquakes and other disturbances of ocean surface water.

Can also be caused by icebergs falling from glaciers and volcanic eruptions.

They’re also called seismic sea waves.

They can have wavelengths of 150 miles.

They can travel at over 450 miles per hour!

A wave formed off of Alaska can reach Hawaii in only 5 hours.

In the open ocean, a tsunami may only have a wave height of a few feet.

As the wave approaches shallow water, it builds to heights that can reach greater than 100 feet.

The 2004 Indian Ocean Tsunami was caused by an earthquake off the coast of Indonesia.

The earthquake was the 2nd largest EVER recorded at a magnitude of 9.3

It was one of the deadliest natural disasters in recorded history. Indonesia, Sri Lanka, India, and Thailand were hardest hit.

229,866 people were lost, including 186,983 dead and 42,883 missing

Japan was hit by an enormous earthquake on March 11, 2011, that triggered a deadly 23-foot tsunami.

Caused by 8.9 to 9.0 earthquake, which is the largest in Japan’s history.

15,839 deaths, 5,950 injured, and 3,642 people missing, as well as over 125,000 buildings damaged or destroyed.

About 26 hours after the earthquake, an explosion in reactor No. 1 at the Fukushima Daiichi Nuclear Power Station caused one of the buildings to crumble to the ground. The cooling system at the reactor failed shortly after the earthquake.

Residents within a 20 km (12 mi) radius of the Fukushima I Nuclear Power Plant and a 10 km (6.2 mi) radius of the Fukushima II Nuclear Power Plant were evacuated.

http://oceanservice.noaa.gov/news/features/dec11/japan-tsunami-debris.html

tsunami 101 Footage 1 Footage 2

Waves of Destruction…..

The rise and fall in sea level is called a tide.

Caused by a giant wave.One low-tide/high-tide cycle takes about 12 hrs and 25 min.

Tidal range is the difference in ocean level between high-tide and low-tide

Two big bulges of water form on the Earth:◦one directly under the moon ◦another on the exact opposite side

As the Earth spins, the bulges follow the moon.

Spring Tides◦Earth, Moon, and Sun are lined up (full or new moon)

◦High Tides are higher and Low Tides are lower than normal

Neap Tides◦Earth, Moon, and Sun form right angles (half moon)

◦High Tides are lower and Low Tides are higher than normal