New! Sign up for our free email newsletter.
Reference Terms
from Wikipedia, the free encyclopedia

Tide

Tides are the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the Earth. Tides cause changes in the depth of the sea, and also produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation. The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides.

The changing tide produced at a given location on the Earth is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of the rotation of the Earth and the local bathymetry (the underwater equivalent to topography or terrain). Though the gravitational force exerted by the Sun on the Earth is almost 200 times stronger than that exerted by the Moon, the tidal force produced by the Moon is about twice as strong as that produced by the Sun. The reason for this is that the tidal force is related not to the strength of a gravitational field, but to its gradient. The field gradient decreases with distance from the source more rapidly than does the field strength; as the Sun is about 400 times further from the Earth than is the Moon, the gradient of the Sun's field, and thus the tidal force produced by the Sun, is weaker.

Related Stories
 


Earth & Climate News

August 1, 2025

A Penn State-led research team has unraveled the long-standing mystery of how lightning begins inside thunderclouds. Their findings offer the first quantitative, physics-based explanation for lightning initiation—and a glimpse into the stormy ...
A jaw-dropping 515-mile lightning bolt lit up the skies from Texas to Kansas City, smashing previous records and reshaping our understanding of extreme weather. Thanks to advanced satellite tech, scientists like Randy Cerveny and Michael Peterson ...
A team at the University of Florida used drones and smart modeling to accurately count over 41,000 endangered turtles nesting along the Amazon’s Guaporé River—revealing the world’s largest known turtle nesting site. Their innovative ...
Researchers are exploring AI-powered digital twins as a game-changing tool to accelerate the clean energy transition. These digital models simulate and optimize real-world energy systems like wind, solar, geothermal, hydro, and biomass. But while ...
Deep in Serbia's Jadar Valley, scientists discovered a mineral with an uncanny resemblance to Superman's Kryptonite both in composition and name. Dubbed jadarite, this dull white crystal lacks the ...
Mesopelagic fish, long overlooked in ocean chemistry, are now proven to excrete carbonate minerals much like their shallow-water counterparts—despite living in dark, high-pressure depths. Using the deep-dwelling blackbelly rosefish, researchers ...
For over two decades, satellites have quietly documented a major crisis unfolding beneath our feet: Earth's continents are drying out at unprecedented rates. Fueled by climate change, groundwater ...
Air pollution isn't just bad for your lungs—it may be eroding your brain. In a sweeping review covering nearly 30 million people, researchers found that common pollutants like PM2.5, nitrogen ...
A new eco-friendly plastic called LAHB has shown it can biodegrade even in the extreme environment of the deep ocean, unlike conventional plastics that persist for decades. In real-world underwater testing nearly a kilometer below the surface, LAHB ...
In 2023, the world’s oceans experienced the most intense and widespread marine heatwaves ever recorded, with some events persisting for over 500 days and covering nearly the entire globe. These ...
Imagine concrete that not only survives wildfires and extreme weather, but heals itself and absorbs carbon from the air. Scientists at USC have created an AI model called Allegro-FM that simulates billions of atoms at once, helping design futuristic ...
Scientists have discovered that pairing bread wheat with a special soil fungus can significantly enhance its nutritional value. This partnership leads to bigger grains rich in zinc and phosphorus—without increasing anti-nutrients that block ...

Latest Headlines

updated 12:56 pm ET