Earth’s Oceans

Oceans Oceanography- the study of Earth’s oceans Water could have originated one of two ways on Earth: Comets hitting Earth Volcanic Eruptions emitting gasses

Oceans Modern Oceanography Sonar Satellites Today we can use SONAR and satellites to study the oceans. Satellites such as the Topex/Poseidon monitor the ocean’s surface temperatures, currents, and wave conditions. Satellites Modern Oceanography Sonar

Oceans cover approximately 71% of the Earth’s surface Ocean Water Oceans cover approximately 71% of the Earth’s surface

Ocean Water Oceans cover about: 61% of the northern hemisphere 81% of the southern hemisphere Northern Hemisphere Southern Hemisphere

Chemical Properties of Seawater Ocean water is made up of several different elements that make it “salty”

Chemical Properties of Seawater Salinity is a measure of the amount of dissolved salts in seawater. Salinity is measured in grams of salt per kilograms of water, or parts per thousand (ppt)

Chemical Properties of Seawater The average salinity of seawater is 35 ppt or 3.5%

Chemical Properties of Seawater Salinity can be increased by: Weathering and erosion of rock Volcanic activity Evaporation Salinity can be decreased by: Precipitation Runoff Iceberg and sea ice melting

Ocean Layers The ocean can be divided into 3 layers based on temperature Surface layer Transitional thermocline Bottom layer Surface Layer Thermocline Bottom Layer

Thermocline - a zone of rapid temperature change Thermocline - a zone of rapid temperature change. As depth INCREASES temperature DECRESES

Water Density Water density is affected by temperature and salinity Cold water is more dense and sinks to the bottom Warm water is less dense and rises Salinity Higher salinity leads to increased density Higher density water sinks.

Currents Density Currents- caused by the differences in temperature and salinity in deep water Surface Currents- caused by winds.

Gulf Stream From North America to Europe, follows the “Westerlies” as a Surface Current. 300x flow of Amazon Cold+salt = dense water In the North Atlantic Ocean, the water becomes so dense - begins to sink down through less salty and less dense water: Density Current

Gyres - circular ocean currents caused by landmasses Coriolis effect – ocean currents in the northern hemisphere are deflected to the right and currents in the southern hemisphere are deflected to the left Upwelling - Vertical movement of ocean water

Tides Tides - the periodic rise and fall of ocean levels

Neap Tides Spring Tides Occur when the Sun, Moon and Earth form a right angle. High tides are lower, low tides higher than normal Spring Tides Occur when Sun, Moon and Earth are aligned High tides are higher and low tides lower than normal

Ocean Waves Wavelength- distance from one point to the same point on the next wave Crest- top of a wave Trough- bottom of a wave Wave- rhythmic movement that carries energy through matter or space

Breakers- waves whose bottom is moving slower than the top due to friction