The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. The depth of the photic zone can be greatly affected by seasonal turbidity. The worlds oceans as seen from the South Pacific Ocean (from Okeanos, Greek for river, the ancient Greeks noticed that a strong current flowed off Gibraltar, and assumed it was a great river); covers almost three quarters (71%) of the surface of the Earth, and nearly half of the... Prism splitting light Sunlight in the broad sense is the total spectrum of electromagnetic radiation given off by the Sun. ... Leaf. ... Turbidity standards of 10, 100, and 1000 NTU Turbidity is a cloudiness or haziness of water (or other liquid) caused by individual particles that are too small to be seen without magnification, thus being much like smoke in air. ...

It extends from the atmosphere-ocean interface downwards to a depth where light intensity falls to 1% of that at the surface (also called euphotic depth), so its thickness depends on the extent of light attenuation in the water column. Typical euphotic depths vary from only several metres in turbid estuaries to around 200 metres in the open ocean. Attenuation is the decrease of the amount, force, magnitude, or value of something. ... Turbidity standards of 10, 100, and 1000 NTU Turbidity is a cloudiness or haziness of water (or other liquid) caused by individual particles that are too small to be seen without magnification, thus being much like smoke in air. ... Estuaries and coastal waters are among the most productive ecosystems on Earth, providing numerous ecological, economic, cultural, and aesthetic benefits and services. ...

Since the photic zone is the only zone of water where primary productivity occurs, an exception being the productivity connected with abyssal hydrothermal vents along mid-oceanic ridges, the depth of the photic zone is generally proportional to the level of primary productivity that occurs in that area of the ocean,. A hydrothermal vent A hydrothermal vent is a fissure in a planets surface from which geothermally heated water issues. ... An oceanic ridge is an underwater mountain range, usually formed by plate tectonics. ...

The transparency of water, which affects the photic zone, is simply measured with a Secchi disk. Secchi disk pattern Created in 1865 by Pietro Angelo Secchi, the Secchi disk is a device used to measure water transparency in open waters of lakes, bays, and the ocean. ...

See also

• Pelagic zone
• Aphotic zone