Ocean current

Ocean surface currents
The bathymetry of the Kerguelen Plateau in the Southern Ocean governs the course of the Kerguelen deep western boundary current, part of the global network of ocean currents.
Coupling data collected by NASA/JPL by several different satellite-borne sensors, researchers have been able to "break through" the ocean's surface to detect "Meddies" – super-salty warm-water eddies that originate in the Mediterranean Sea and then sink more than a half-mile underwater in the Atlantic Ocean. The Meddies are shown in red in this scientific figure.
A recording current meter
A 1943 map of the world's ocean currents

Continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences.

- Ocean current

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Earth

Third planet from the Sun and the only astronomical object known to harbor life.

A photograph of Earth taken by the crew of Apollo 17 in 1972. A processed version became widely known as The Blue Marble.
Planetary disk of a star, the inner ring has a radius equal to Earth and the Sun
Artist's impression of earth during the Archean eon, showing falling meteor, erupting volcano, round stromatolites, and barren landscape
Earth topological map, the area is redder if it is raised higher in real-life
Global map of heat flow from Earth's interior to the surface
Earth's major plates, which are: · · · · ·
Satellite picture of Upsala Glacier, showing mountains, icebergs, lakes, and clouds
Schematic of Earth's magnetosphere, with the solar wind flows from left to right
Earth's rotation imaged by Deep Space Climate Observatory, showing axis tilt
Illustration of the Earth, Earth's orbit, the Sun and the four seasons
Earth's axial tilt and its relation to the rotation axis and planes of orbit
Earth-Moon system seen from Mars
A model of Vanguard 1, the oldest human-made object in Earth orbit
Water is transported to various parts of the hydrosphere via the water cycle
Top of Earth's blue-tinted atmosphere, with the Moon at the background
Fungi are one of the kingdoms of life on Earth.
The seven continents of Earth:
Earth's land use for human agriculture
Change in average surface air temperature since the industrial revolution, plus drivers for that change. Human activity has caused increased temperatures, with natural forces adding some variability.
Earthrise, taken in 1968 by William Anders, an astronaut on board Apollo 8
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More solar energy is received by tropical regions than polar regions and is redistributed by atmospheric and ocean circulation.

Upwelling

Oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface.

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During an El Niño, wind indirectly drives warm water to the South American coast, reducing the effects of cold upwelling

Upwellings that are driven by coastal currents or diverging open ocean have the greatest impact on nutrient-enriched waters and global fishery yields.

Climate

Long-term weather pattern in an area, typically averaged over 30 years.

Average surface air temperatures from 2011 to 2021 compared to the 1956–1976 average. Source: NASA
Observed temperature from NASA vs the 1850–1900 average used by the IPCC as a pre-industrial baseline. The primary driver for increased global temperatures in the industrial era is human activity, with natural forces adding variability.

Other ocean currents redistribute heat between land and water on a more regional scale.

Plankton

Part of the contents of one dip of a hand net. The image contains diverse planktonic organisms, ranging from photosynthetic cyanobacteria and diatoms to many different types of zooplankton, including both holoplankton (permanent residents of the plankton) and meroplankton (temporary residents of the plankton, e.g., fish eggs, crab larvae, worm larvae)
Some marine diatoms—a key phytoplankton group
An amphipod (Hyperia macrocephala)
Diverse assemblages consist of unicellular and multicellular organisms with different sizes, shapes, feeding strategies, ecological functions, life cycle characteristics, and environmental sensitivities.
Sea spray containing marine microorganisms can be swept high into the atmosphere and may travel the globe as aeroplankton before falling back to earth.
Jellyfish are gelatinous zooplankton.
Salmon egg hatching into a sac fry. In a few days, the sac fry will absorb the yolk sac and start feeding on smaller plankton
Tomopteris, a holoplanktic bioluminescence polychaete worm
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Amphipod with curved exoskeleton and two long and two short antennae
Marine phytoplankton cycling throughout water column.
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Diatoms have glass shells (frustules) and also produce much of the world's oxygen
The elaborate silica shells of microscopic marine radiolarians can eventually produce opal
Coccolithophores have chalk plates called coccoliths, and produced the Cliffs of Dover
Planktonic algae bloom of coccolithophores off the southern coast of England
Foraminiferans have calcium carbonate shells and produced the limestone in the Great Pyramids
Pelagibacter ubique, the most common bacteria in the ocean, plays a major role in global carbon cycles
The tiny cyanobacterium Prochlorococcus is a major contributor to atmospheric oxygen
The sea sparkle dinoflagellate glows in the night to produce the milky seas effect
Copepod from Antarctica, a translucent ovoid animal with two long antennae
Herring larva imaged with the remains of the yolk and the long gut visible in the transparent animal
Icefish larvae from Antarctica have no haemoglobin
The sea walnut ctenophore has a transient anus which forms only when it needs to defecate<ref>{{cite magazine| title=Animal with an anus that comes and goes could reveal how ours evolved| author=Michael Le Page| magazine=New Scientist| url=https://www.newscientist.com/article/2195656-animal-with-an-anus-that-comes-and-goes-could-reveal-how-ours-evolved/| date=March 2019}}</ref>
Eel larva drifting with the gulf stream
Antarctic krill, probably the largest biomass of a single species on the planet
Microzooplankton are major grazers of the plankton: two dinoflagellates and a tintinnid ciliate).
Sargassum seaweed drifts with currents using air bladders to stay afloat
Planktonic sea foam bubbles with image of photographer
Macroplankton: a Janthina janthina snail (with bubble float) cast up onto a beach in Maui

Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind).

Sverdrup

Non-SI metric unit of flow, with 1 Sv equal to 1 e6m3/s; it is equivalent to the SI derived unit cubic hectometer per second (symbol: hm3/s or hm3⋅s−1).

Thermohaline circulation

It is used almost exclusively in oceanography to measure the volumetric rate of transport of ocean currents.

Ocean gyre

All of the world's larger gyres
Coriolis effect

In oceanography, a gyre is any large system of circulating ocean currents, particularly those involved with large wind movements.

Boundary current

The main ocean currents involved with the North Pacific Gyre
The world's largest ocean gyres

Boundary currents are ocean currents with dynamics determined by the presence of a coastline, and fall into two distinct categories: western boundary currents and eastern boundary currents.

Season

Division of the year based on changes in weather, ecology, and the number of daylight hours in a given region.

Tropical dry season in Maharashtra, India
Tropical wet season/monsoon in Maharashtra, India
Illumination of Earth at each change of astronomical season
This diagram shows how the tilt of Earth's axis aligns with incoming sunlight around the winter solstice of the Northern Hemisphere. Regardless of the time of day (i.e. the Earth's rotation on its axis), the North Pole will be dark and the South Pole will be illuminated; see also arctic winter. In addition to the density of incident light, the dissipation of light in the atmosphere is greater when it falls at a shallow angle.
Animation of seasonal differences especially snow cover through the year
Four Seasons by Alphonse Mucha (1897)
Four temperate and subpolar seasons: (above) winter, spring, (below) summer, autumn/fall
Note: Distances are exaggerated and not to scale
The annual cycle of insolation (Sun energy, shown in blue) with key points for seasons (middle), quarter days (top) and cross-quarter days (bottom) along with months (lower) and Zodiac houses (upper). The cycle of temperature (shown in pink) is delayed by seasonal lag.
The six modern mid-latitude ecological seasons. From bottom, clockwise: prevernal, vernal, estival, serotinal, autumnal, hibernal
Wet and dry seasons
Illumination of Earth by Sun at the northern solstice.
Illumination of Earth by Sun at the southern solstice.
Diagram of the Earth's seasons as seen from the north. Far right: southern solstice
Two images showing the amount of reflected sunlight at southern and northern summer solstices respectively (watts / m{{sup|2}}).

Seasonal weather fluctuations (changes) also depend on factors such as proximity to oceans or other large bodies of water, currents in those oceans, El Niño/ENSO and other oceanic cycles, and prevailing winds.

Thermohaline circulation

A summary of the path of the thermohaline circulation. Blue paths represent deep-water currents, while red paths represent surface currents.
The global conveyor belt on a continuous-ocean map [ (animation)]
Effect of temperature and salinity upon sea water density maximum and sea water freezing temperature.
Benjamin Franklin's map of the Gulf Stream

Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.

Gulf Stream

Surface temperatures in the western North Atlantic. The North American landmass is black and dark blue (cold), while the Gulf Stream is red (warm). Source: NASA
Benjamin Franklin's chart of the Gulf Stream printed in London in 1769
Evolution of the Gulf Stream to the west of Ireland continuing as the North Atlantic Current
Hurricane Sandy intensifying along the axis of the Gulf Stream in 2012.

The Gulf Stream, together with its northern extension the North Atlantic Drift, is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the United States the veers east near 36 latitude (North Carolina) and moves toward Northwest Europe as the North Atlantic Current.