Waves Waves A Wave is a rhythmic movement

Waves

Waves • A Wave is a rhythmic movement that carries energy through matter or space. • In oceans, waves move through seawater

Waves Caused by: • Wind • Earthquakes • Gravitational force of the Moon and Sun.

Waves On The Beach • Most of the waves we see are at the beach.

Waves On The Beach • As the wave travels in shallower water it slows and eventually falls forward as a breaker.

Wind or Storm Waves • The most familiar waves are wind generated.

Wind or Storm Waves • Three things determine how large these waves can become.

1. Wind Speed • This is the speed that the wind is blowing. • This is usually measured in knots or nautical miles per hour.

2. Fetch • Fetch refers to the distance over which the wind blows. • If a wind blows over thousands of miles the waves can get much larger than blowing across a small pond.

3. Duration • Duration refers to the time over which the wind blows. • Winds in some areas may blow strong for long periods of time which can produce large waves.

Parts of a Wave • Crest – highest point of a wave • Trough – lowest point of a wave • Wavelength – horizontal distance between two crests or two troughs • Wave Height – vertical distance between the crest and the trough

Wavelength Wave Height Crest Still Water Trough Wave Parts

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

Wave Movement • The crest outruns the trough and the crest collapses – it breaks against the shore. • In this case, water does move forward and backward.

Waves Caused by Wind • When wind blows across a body of water, friction causes the water to move along with the wind.

Tsunamis • Are produced by earthquakes and other seismic disturbances. aka seismic sea waves.

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

Tsunamis • They are very long, fast moving waves. • They can have wavelengths of 150 miles. • They can travel at over 450 miles per hour! As fast as a jet!

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

The Danger of Tsunamis • As the wave approaches shallow water, it builds to heights that can reach greater than 100 feet.