Notes-Ocean Circulation, Waves and Tides
Ocean water is in constant motion powered by many different forces. ______________
generate surface currents and waves can impact upwelling. Ocean currents are masses of
ocean water that flow from one place to another. They can be on the surface or deep
below. __________________ _______________ develop from friction between the
ocean and the wind that blows across its surface. Some are small and some are large and
cover much of the horizontal movements of surface waters that are closely related to the
circulation __________________ of the atmosphere. _______________ are huge
circular-moving current systems in the oceans. There are ____ main gyres in the world.
Beside the wind there are other factors that affect surface currents. The Coriolis effect is
the deflection of the currents based on the Earth’s ______________. Currents are
deflected to the right in the Northern Hemisphere and to the left in the Southern
Hemisphere.
Open Ocean Currents and Climate
Ocean currents have an important effect on climates. When _______________ from
low-latitude regions move into higher latitudes, they transfer _________ from warmer to
cooler areas on Earth. An example is the Gulf Stream off the coast of the Southeastern
U.S. brings ____________ water from the equator up to the North Atlantic Current which
allows for Great Britain and much of Western Europe to be warmer during the winter
than one would expect at that latitude. The opposite affect happens with cold water
currents. As ___________ water currents travel toward the equator, they help moderate
the warm temperatures of adjacent land areas. An example is the California Current.
The ocean currents transport ____% of the earth’s heat from the equator to the poles
where the global winds transport the other ____%. Upwelling is the rising of cold water
from deeper layers to replace wind-blown warmer surface water. Coastal upwelling takes
place along the coast of California, the West coast of South America and the West coast
of Africa. As wind blows toward the equator parallel to these __________, the Coriolis
effect cause surface water to move away from the shore clearing the way for the
upwelling to occur.
Deep-Ocean Circulation
Deep-Ocean currents have a vertical component as well as horizontal movement.
_______________ _____________ are vertical currents of ocean water resulting from
differences in density. An increase in sea-water density can be caused by a
_____________ in temperature or an ______________ in salinity. Most water involved
in deep-ocean density currents begins in high latitudes at the surface. _______________
water becomes cold, and its salinity increases as the sea ice forms. When the water
becomes dense enough it ____________ initiating the deep-ocean density currents.
Density currents can also result from increased _________________ due to evaporation.
A simple model of ocean circulation is similar to a ________________ ________ that
travels from the Atlantic Ocean through the Indian and Pacific oceans and back again. In
this model warm water in the ocean’s upper layers travels toward the poles. When the
water reaches the poles it cools and salinity ________________ causing the water to sink
and start moving toward the __________________. When the cold dense water reaches
the equator _____________________ occurs completing the cycle. The conveyor belt
moves around the globe influencing global ________________ by converting warm
water to cold water and releasing ______________ into the atmosphere.
Waves and Tides
Ocean waves are energy traveling along the boundary between ocean and atmosphere
created by ____________. Waves can travel for thousands of miles when created by the
winds of storms. The height, length, and period that are eventually achieved by a wave
depend on three factors: 1)wind ____________; 2) length of time the wind has blown;
and fetch, which is the distance the wind has traveled over open water. Waves travel in a
circular, rolling motion this allows energy to move forward through the water while the
individual water particles that transmit the ____________ move around in a circle.
Ocean tides result from differences in the gravitational attraction exerted upon different
parts of the Earth’s surface by the _______________, and to a lesser extent, by the Sun.
Newton identified in the late 1600’s that the gravitational pull of the Moon is the major
cause of tides. The gravitational pull of the Moon is ________________ on the side of
the earth nearest the Moon. As a result the ocean on the side of the Earth facing the
Moon bulges slightly, causing a high tide within the area of the bulge. There is also a
high tide on the opposite side of the Moon because of the outward force generated by the
earth’s ____________________. So there are always two high tides and two low tides
somewhere on the planet.