Currents, Waves, Tides
The movement of ocean water is made by the differences in density and temperate, by wind, and by the moons gravitational pull. An ocean current is a movement of ocean water hat follows a regular pattern. Currents are influenced by weather, the earth's rotation, and the position of the continents. There are different types of currents that blow the ocean, for example, surface currents. Surface currents are horizontal movements of ocean water that is caused by wind and that occurs at or near the oceans surface. A example of a surface current is the Gulf stream, which is a surface current that moves warm waters from lower latitudes to higher latitudes. Surface currents are controlled by three things: the Coriolis effect, global winds, and continental deflections. Global winds are winds that across the Earth's surface and create a ripple effect on the waters. The Coriolis effect the apparent curving of the path of a moving object from an otherwise straight path due to the Earth's rotation. Continental deflections is when the continents rise above sea level and then when the surface currents meet the continents they change direction. Cold water currents and warm water currents can pass each other, collide with each other, and go to the same place. Upwelling is the process of in which cold nutrients rich from the deep ocean rises to the surface and replaces the warm surface water. The elements in this water gives the organisms here the nutrients they need to live. Deep currents are stream-like movements of ocean water far below the surface. These types of currents are not made by wind, the are made where density is highest. The difference in the density and salinity causes the movement of deep currents.
Waves are made up of two things, a crest and a trough, which are the measurements of the height of a wave and the length of a wave. Waves are created by the winds energy across the surface of the ocean. They travel through the water at or near the oceans surface, when the water moves in a up and down movement. Wind made waves are deep water waves or shallow water waves, depending on how deep the height of the wave is compared to depth of the water. When waves hit the shore at a certain angle, the create undertow or a longshore current. Undertow is a subsurface current that is near the shore and that pulls things out to sea. A longshore current is a water current that travels near and parallel to the shoreline. Tsunamis are dangerous natural disaster waves that can be very destructive and deadly to people and things in them. Storm surge is a local rise in sea level near the shore caused by strong winds from a storm, such as from a hurricane.
Tides are daily changes in the level of ocean water influenced by the sun and moon described by Sir Isaac Newton's theories on the principle of gravitation in 1687. There are four types of tides: high tides, low tides, neap tides, and spring tides. Spring tides are tides of increased range that occurs two times a month, at the new and full moons. Neap tides are tides of minimum range that occurs during the first and third quarters of the moon. High tide occurs on the part of the earth that is closest to the moon and also on the opposite side of the earth. Low tide occurs on the area of the earth that is not facing the moon or on the opposite side f the side that is facing the moon.