Normally, warmer water is transported westward in the Pacific Ocean by the southeast trade winds until it accumulates near Indonesia. This warm water in the western Pacific Ocean causes low air pressure and high rainfall. Warmer water causes the air above the ocean's surface to warm and rise, leaving an area of lower pressure. More rainfall is associated with lower air pressure. Meanwhile, the eastern Pacific Ocean has high air pressure and less rainfall.
Every 3 to 10 years, the southeast trade winds weaken, allowing the warm water to flow further eastward toward South America. This event can have devastating effects on marine life, including coral reefs, and fisheries. South America experiences wetter than average weather while North America experiences mild, but stormier winter weather.
This phenomenon is known as Ekman Transport , and is an important concept for understanding coastal upwelling and downwelling. Gravity then pulls the water back down the slope to an area of lower elevation, fueling further rotation of the gyre. Currents along the western side of gyres are called western boundary currents , while currents along the eastern side of gyres are called eastern boundary currents.
The westerly flowing currents that are created where the North Pacific and South Pacific gyres meet are known as the equatorial currents oceanservice. Western boundary currents flow deeper and stronger than eastern boundary currents. This means that cool, nutrient-rich water is closer to the surface in eastern boundary currents than western boundary currents. Plastic is ubiquitous in our everyday lives. Some plastics we can reuse or recycle—and many play important roles in areas like medicine and public safety—but other items, such as straws, are designed for only one use.
In fact, more than 40 percent of plastic is used only once before it is thrown away, where it lingers in the environment for a long, long time. It often breaks down into smaller and smaller particles, called microplastics, which can be ingested by both animals and people. Fortunately, there are things we can do to help—like stop using plastic bags, straws, and bottles, recycling when we can, and disposing of waste properly.
Use these classroom resources to teach about ocean plastics and check back for more coming later this year! Scientists across the globe are trying to figure out why the ocean is becoming more violent and what, if anything, can be done about it. Ocean currents, including the ocean conveyor belt, play a key role in determining how the ocean distributes heat energy throughout the planet, thereby regulating and stabilizing climate patterns.
A current is the steady, predictable movement of a fluid within a larger body of that fluid. Fluids are materials capable of flowing and easily changing shape. A gyre is a circular ocean current formed by the Earth's wind patterns and the forces created by the rotation of the planet. Join our community of educators and receive the latest information on National Geographic's resources for you and your students.
Skip to content. Image Rubber Duck on the Beach A rubber duck washed up on the beach after being carried out in the ocean. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Coriolis effect. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Media If a media asset is downloadable, a download button appears in the corner of the media viewer.
Because the bottles are both of equal volume, the liquid in the heavier bottle is denser. If you put the two liquids together, the one with greater density would sink and the one with lower density would rise. Two major factors determine the density of ocean water: salinity the amount of salt dissolved in the water and temperature Figure The more salt that is dissolved in the water, the greater its density will be.
Temperature also affects density: the colder the temperature, the greater the density. This is because temperature affects volume but not mass. Colder water takes up less space than warmer water except when it freezes. So, cold water has greater density than warm water. The blue arrows are deep currents and the red ones are surface currents.
A water particle in the convection cycle can take years to complete the cycle. More dense water masses will sink towards the ocean floor. Just like convection in air, when denser water sinks, its space is filled by less dense water moving in. This creates convection currents that move enormous amounts of water in the depths of the ocean. Why is the water temperature cooler in some places? Water cools as it moves from the equator to the poles via surface currents. Cooler water is more dense so it begins to sink.
As a result, the surface currents and the deep currents are linked.
0コメント