Environmental Engineering Reference
In-Depth Information
Ocean Currents
Water in the oceans is in constant motion, known as
currents.
Currents are influenced by the weather, location
of the continents, and rotation of the Earth. There are two types of currents:
•
Surface currents:
Surface currents are the movements of water at or near the surface of the ocean. The
global winds, Coriolis effect, and position of the continents control them. The Coriolis effect deflects not
only air but water. Surface currents in the Northern Hemisphere turn clockwise; in the Southern Hemi-
sphere, they turn counterclockwise. Water temperature is another factor that influences ocean surface
currents. Cold water currents begin at the poles and move cold water over the planet. Warm water cur-
rents start near the equator and move warm water throughout the world. Surface currents can be shallow
or reach several hundreds of meters in depth. They can be short movements across the top of the surface
or can travel hundreds of miles. The Gulf Steam coming out of the Gulf of Mexico and moving up the
eastern coastline of the United States is an example of a surface current that can be 800 to 1,200 meters
deep.
•
Deep ocean currents:
Deep ocean currents are located far below the surface and are created by differen-
ces in the density of water rather than surface winds and other effects. Density is a factor of salinity and
temperature. The deep warm water currents move toward the poles where ice forms, increasing the salin-
ity of the water. This increases the density of the water, and it sinks to the ocean floor, where this cold,
dense water flows as the deep currents.
Soil Dynamics
Soil is more than simply dirt. It is a complex system that includes eroded rock material, organic matter, nutri-
ents, air, water, and living organisms. The air and water are held within pore spaces throughout the soil. Be-
cause soil is largely composed of weathered rock, soil types depend on which type of rock is the parent materi-
al in a given location. Ultimately, this basic rock material is one of the factors that affects the type of vegeta-
tion that grows in specific locations.
