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3. What is a current?

**What is a current?**  The term "current" describes **the motion of the ocean**. It appears that your browser doesn't support HTML5 video.
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  You know about ocean tides, but how much do you know about ocean currents? Watch our three-minute video podcast to learn what puts the motion in the ocean. Ocean currents are driven by wind, water density differences, and tides. Oceanic currents describe the movement of water from one location to another.  Currents are generally measured in meters per second or in knots (1 knot = 1.85 kilometers per hour or 1.15 miles per hour). Oceanic currents are driven by three main factors: **1. The rise and fall of the tides.** Tides  create a current in the oceans, which are strongest near the shore, and in bays and  estuaries along the coast. These are called "tidal currents." Tidal  currents change in a very regular  pattern and can be predicted for future dates. In some locations, strong tidal currents can travel at speeds of eight knots or more. **2. Wind.** Winds drive currents  that are at or near the ocean's surface. Near coastal areas winds tend to drive currents on a localized scale and can result in phenomena like coastal upwelling.  On a more global scale, in the open ocean, winds drive currents that circulate water for thousands of miles throughout the ocean basins. **3. Thermohaline circulation.** This is a  process driven by density differences in water due to temperature  (thermo) and salinity (haline) variations in different parts of the ocean.  Currents driven by thermohaline circulation occur at both deep and  shallow ocean levels and move much slower than tidal or surface  currents. Currents affect the Earth's climate by driving warm water from the Equator and cold water from the poles around the Earth.  The warmGulf Stream, for instance, brings milder winter weather to Bergen, Norway, than to New York, much further south.
 More **Information** Tides & Currents: Center for Operational Oceanographic Products and Services NOAA CoastWatch Ocean Currents (video)   Get **Social** Social
  **Last updated:** 08/22/23 **Author:** NOAA How to cite this article Contact Us


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