Ocean Motions Information to help you along in Earth science

Does this look familiar? Look closer………..

What’s in the ocean?

Sea Surface Temperature

The Ocean  The ocean provides us with many things. It is more than a place for swimming, boating, and other forms of recreation.

Ocean facts  Oceans serve as a source of food, energy, and minerals.

Ocean facts…  But above all else, the sea helps keep the earth's climate healthy by regulating air temperature and by supplying moisture to produce rainfall.

More facts….  If there were no ocean, life would not exist on our planet

Waves

Waves  Wave- the movement of energy through a body of water.  Most waves form when winds blowing across the water’s surface transmit their energy to the water.  The size of a wave depends on the strength of the wind, the length of time it blows, and the distance over which the wind blows.

  Waves may appear to carry water toward the shore, but the water does not move. If the water moved it would pile up on the coasts of every continent.   THE ENERGY OF THE WAVE MOVES TOWARD THE SHORE, THE WATER ITSELF REMAINS WHERE IT WAS.

 As waves nears the shore the water is more shallow and they slow as they touch the ocean floor. The speed changes the shape of the wave. Higher wave height, lower wavelength.  At a certain height the crest topples over and break on the shore forming surf. This creates undertow, carrying sand, shells, etc and could be harmful to swimmers.

Characteristics of waves

Watch this wave *Watch the water droplet move in a vertical circle as the wave passes. The droplet moves forward with the wave's crest and backward with the trough.*

Tides  The daily rise and fall of Earth’s waters on its continents are called tides.  Tides are caused by the interaction of Earth, the moon, and the sun.  The gravitational pull of the moon creates a bulge of water on the side of Earth that is facing the moon.  Unlike surface waves, tides happen regularly no matter how the wind blows.

What causes the tides?  The gravitational pull of the moon mostly, and the gravitational pull of the sun secondly

What causes the tides?

Tides  There are 2 high tides and 2 low tides each day……  Each high tide is about 12 hours apart and Each low tide is about 12 hours apart.

At high tide and low tide

2 Types of Tides  Neap Tides- Occur at the first and third quarter moon, when the sun, moon, and Earth are lined up to form a right angle  Spring Tides- Occur when the new and full moon, sun, and Earth are lined up

NEAP TIDE

Spring TIDE

CURRENTS  Current- a large stream of moving water that flows through the oceans. –Example: If you stir a cup of cocoa you have created a current  Surface currents, which affect water to a depth of several hundred meters, are driven mainly by winds.  The surface currents follow the wind patterns of the globe, which are circular patterns, because of the Earth’s rotation.

CURRENTS, continued  The effect of Earth’s rotation on the direction of winds and currents is called the Coriolis effect.  Northern Hemisphere-currents curve to the right  Southern Hemisphere-currents curve to the left

 Surface Currents –Influence climate of land –Warm water from the equator is spread to other places on Earth  (Example: Iceland is warmed by the Gulf Stream that turns an area that should be very cold to one with a mild climate)  Types of Surface Currents –Gulf Stream current and North Atlantic Drift are warm surface currents that affect the climate of land

Affecting climate  Surface currents warm or cool the air above it affecting the climate in that location. –Climate- The weather in some location averaged over a long period of time  Wind picks up moisture, so areas that have warm surface currents tend to have rainier weather. Areas that receive cold currents, tend to be drier, because cold air, holds less moisture.

Deep currents  Are caused by differences in density, not surface winds  The density of water depends on salinity and temperature  Flow slower than surface currents

Deep currents  Warm water from the equator moves towards the poles and cools off  The water becomes dense and sinks  The water then flows along the ocean floor as a deep current

Upwelling  An upward movement of cold water from the oceans depths  Bring up tiny ocean organisms, minerals, and other nutrients

El Nino  An abnormal climate event that occurs every 2-7 years in the Pacific ocean  It brings unusual patterns of winds

Ocean Currents