User:Siva.tecz/sandbox

Source: Wikipedia, the free encyclopedia.
"Natural" and "Natural World" redirect here. For other uses, see Nature (disambiguation) and Natural (disambiguation).
Hopetoun Falls, Australia
Bachalpsee in the Swiss Alps
Lightning strikes during the eruption of the Galunggung volcano, West Java, in 1982.

Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the

subatomic to the cosmic
.

The word nature is derived from the Latin word natura, or "essential qualities, innate disposition", and in ancient times, literally meant "birth".[1] Natura was a Latin translation of the Greek word physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord.[2][3] The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socratic philosophers, and has steadily gained currency ever since. This usage was confirmed during the advent of modern scientific method in the last several centuries.[4][5]

Within the various uses of the word today, "nature" often refers to geology and wildlife. Nature may refer to the general realm of various types of living plants and animals, and in some cases to the processes associated with inanimate objects – the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth, and the matter and energy of which all these things are composed. It is often taken to mean the "natural environment" or wilderness–wild animals, rocks, forest, beaches, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. For example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human consciousness or a human mind. Depending on the particular context, the term "natural" might also be distinguished from the unnatural, the supernatural, or synthetic.

Earth

Main articles: Earth and Earth science
View of the Earth, taken in 1972 by the Apollo 17 astronaut crew. This image is the only photograph of its kind to date, showing a fully sunlit hemisphere of the Earth.

Precipitation varies widely with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere
.

Earth has evolved through geological and biological processes that have left traces of the original conditions. The

tectonic plates. The interior remains active, with a thick layer of plastic mantle and an iron-filled core that generates a magnetic field
.

The atmospheric conditions have been significantly altered from the original conditions by the presence of life-forms,[7] which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods,[8] and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.[9][10]

Geology

Main article: Geology
plate tectonic
boundaries.

Geology is the

natural hazards, some Geotechnical engineering fields, and understanding past climates
and environments.

Geological evolution

The geology of an area evolves through time as rock units are deposited and inserted and deformational processes change their shapes and locations.

Rock units are first emplaced either by

intrusions such as batholiths, laccoliths, dikes, and sills
, push upwards into the overlying rock, and crystallize as they intrude.

After the initial sequence of rocks has been deposited, the rock units can be

transform boundaries, respectively, between tectonic plates
.

Historical perspective

Main articles:
History of the Earth and Evolution
Plankton inhabit oceans, seas and lakes, and have existed in various forms for at least 2 billion years.[11]
An animation showing the movement of the continents from the separation of Pangaea until the present day.

Earth is estimated to have formed 4.54 billion years ago from the

solar nebula, along with the Sun and other planets.[12] The moon formed roughly 20 million years later. Initially molten, the outer layer of the planet cooled, resulting in the solid crust. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, most or all of which came from ice delivered by comets, produced the oceans and other water sources.[13] The highly energetic chemistry is believed to have produced a self-replicating molecule around 4 billion years ago.[14]

Continents formed, then broke up and reformed as the surface of Earth reshaped over hundreds of millions of years, occasionally combining to make a supercontinent. Roughly 750 million years ago, the earliest known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia which broke apart about 540 million years ago, then finally Pangaea, which broke apart about 180 million years ago.[15]

There is significant evidence that a severe glacial action during the Neoproterozoic era covered much of the planet in a sheet of ice. This hypothesis has been termed the "Snowball Earth", and it is of particular interest as it precedes the Cambrian explosion in which multicellular life forms began to proliferate about 530–540 million years ago.[16]

Since the Cambrian explosion there have been five distinctly identifiable mass extinctions.[17] The last mass extinction occurred some 65 million years ago, when a meteorite collision probably triggered the extinction of the non-avian dinosaurs and other large reptiles, but spared small animals such as mammals, which then resembled shrews. Over the past 65 million years, mammalian life diversified.[18]

Several million years ago, a species of small African

Great Oxygenation Event, produced by the proliferation of algae during the Siderian
period, required about 300 million years to culminate.

The present era is classified as part of a mass extinction event, the Holocene extinction event, the fastest ever to have occurred.[19][20] Some, such as E. O. Wilson of Harvard University, predict that human destruction of the biosphere could cause the extinction of one-half of all species in the next 100 years.[21] The extent of the current extinction event is still being researched, debated and calculated by biologists.[22]

Atmosphere, climate, and weather

Lightning
Blue light is scattered more than other wavelengths by the gases in the atmosphere, giving the Earth a blue halo when seen from space
A tornado in central Oklahoma
Main articles: Atmosphere of Earth, Climate, and Weather

The atmosphere of the Earth serves as a key factor in sustaining the planetary

inert gases, carbon dioxide, etc.; but air also contains a variable amount of water vapor. The atmospheric pressure declines steadily with altitude, and has a scale height of about 8 kilometres at the Earth's surface: the height at which the atmospheric pressure has declined by a factor of e
(a mathematical constant equal to 2.71...).[23][24] The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.

Terrestrial weather occurs almost exclusively in the

polar regions
much colder.

Weather can have both beneficial and harmful effects. Extremes in weather, such as

hurricanes and cyclones
, can expend large amounts of energy along their paths, and produce devastation. Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals which depend on its growth for their food.

The planetary climate is a measure of the long-term trends in the weather. Various factors are known to influence the climate, including ocean currents, surface albedo, greenhouse gases, variations in the solar luminosity, and changes to the planet's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including ice ages.

The climate of a region depends on a number of factors, especially

southern
hemispheres experience opposite seasons.

Weather is a chaotic system that is readily modified by small changes to the environment, so accurate weather forecasting is currently limited to only a few days.[citation needed] Overall, two things are currently happening worldwide: (1) temperature is increasing on the average; and (2) regional climates have been undergoing noticeable changes.[25]

Water on Earth

The Iguazu Falls on the border between Brazil and Argentina
Main article: Water

Water is a

precipitation.[28][29] Oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds
0.6%. Additionally, a minute amount of the Earth's water is contained within biological bodies and manufactured products.

Oceans

A view of the Atlantic Ocean from Leblon, Rio de Janeiro.
Earth's ocean

Main five oceans division:

Further subdivision:

Marginal seas
Main article: Ocean

An

World Ocean or global ocean.[30][31] This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.[32]

The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria: these divisions are (in descending order of size) the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean. Smaller regions of the oceans are called seas, gulfs, bays and other names. There are also salt lakes, which are smaller bodies of landlocked saltwater that are not interconnected with the World Ocean. Two notable examples of salt lakes are the Aral Sea and the Great Salt Lake.

Lakes

Lake Mapourika, New Zealand
Main article: Lake

A

physical feature), a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is, it is not global) and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river.[33][34] The only world other than Earth known to harbor lakes is Titan, Saturn's largest moon, which has lakes of ethane, most likely mixed with methane. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds. Natural lakes on Earth are generally found in mountainous areas, rift zones, and areas with ongoing or recent glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last Ice Age
. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.

Ponds

The Westborough Reservoir (Mill Pond) in Westborough, Massachusetts.
Main article: Pond

A pond is a

current speed. While currents in streams are easily observed, ponds and lakes possess thermally driven microcurrents and moderate wind driven currents. These features distinguish a pond from many other aquatic terrain features, such as stream pools and tide pools
.

Rivers

The Nile river in Cairo, Egypt's capital city
Main article: River

A

springs, and the release of stored water in natural ice and snowpacks (i.e., from glaciers
).

Streams

A rocky stream in Hawaii
Main article: Stream

A stream is a flowing body of water with a

riparian ecology
and others.

Ecosystems

Loch Lomond in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period of time.[38]
Lush green Aravalli Mountain Range in the Desert country-Rajasthan, India. A wonder how such greenery can exist in hot Rajasthan, a place well known for its Thar Desert
An aerial view of a human ecosystem. Pictured is the city of Chicago
Main articles: Ecology and Ecosystem

Ecosystems are composed of a variety of

biotic components that function in an interrelated way.[39] The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun
, water, and living organisms.

Central to the ecosystem concept is the idea that

environment. Eugene Odum, a founder of ecology, stated: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an ecosystem."[40] Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves as well as with their environment.[41] The human ecosystem concept is grounded in the deconstruction of the human/nature dichotomy and the premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.[citation needed
]

A smaller unit of size is called a microecosystem. For example, a microsystem can be a stone and all the life under it. A macroecosystem might involve a whole ecoregion, with its drainage basin.[42]

Wilderness

European Beech forest in Biogradska Gora National Park, Montenegro
.
Main article: Wilderness

Wilderness is generally defined as areas that have not been significantly modified by

fauna that may be difficult to recreate in zoos, arboretums or laboratories
.

Life

Female mallard and ducklings – reproduction is essential for continuing life
Main articles: Life, Biology, and Biosphere

Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction.[44] Life may also be said to be simply the characteristic state of organisms.

Properties common to terrestrial organisms (

fungi, protists, archaea and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce. An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made analogs of life
may also be considered to be life.

The

geophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere (rocks), hydrosphere (water), and atmosphere (air). Currently the entire Earth contains over 75 billion tons (150 trillion pounds or about 6.8×1013 kilograms) of biomass (life), which lives within various environments within the biosphere.[45]

Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence.[46] More than 2 million species of plant and animal life have been identified to date,[47] and estimates of the actual number of existing species range from several million to well over 50 million.[48][49][50] The number of individual species of life is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis.[51][52] The total number of species is presently in rapid decline.[53][54][55]

Evolution

Amazon Rainforest shared between Colombia and Brazil. The tropical rainforests of South America contain the largest diversity of species on Earth.[56][57]
Main article: Evolution

Life is only known to exist on the planet Earth.(cf

origin of life is still a poorly understood process, but it is thought to have occurred about 3.9 to 3.5 billion years ago during the hadean or archean eons on a primordial earth that had a substantially different environment than is found at present.[58] These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of evolution by natural selection
resulted in the development of ever-more diverse life forms.

Species that were unable to adapt to the changing environment and competition from other life forms became extinct. However, the fossil record retains evidence of many of these older species. Current fossil and DNA evidence shows that all existing species can trace a continual ancestry back to the first primitive life forms.[58]

The advent of

ultraviolet radiation
, life colonized the surface of Earth.

Microbes

A microscopic mite Lorryia formosa.
Main article:
Microbe

The first form of life to develop on the Earth were microbes, and they remained the only form of life on the planet until about a billion years ago when multi-cellular organisms began to appear.

Protista
.

These life forms are found in almost every location on the Earth where there is liquid water, including the interior of rocks within the planet.[61] Their reproduction is both rapid and profuse. The combination of a high mutation rate and a

pathogenic
and can post health risk to other organisms.

Plants, animals and microbes

Main articles: Plant and Animal
plant species
animal species

Originally

algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Bacterial life is sometimes included in flora,[64][65]
and some classifications use the term bacterial flora separately from plant flora.

Among the many ways of classifying

plants are by regional floras, which, depending on the purpose of study, can also include fossil flora, remnants
of plant life from a previous era. People in many regions and countries take great pride in their individual arrays of characteristic flora, which can vary widely across the globe due to differences in climate and terrain
.

Regional floras commonly are divided into categories such as native flora and agricultural and garden flora, the lastly mentioned of which are intentionally grown and cultivated. Some types of "native flora" actually have been introduced centuries ago by people migrating from one region or continent to another, and become an integral part of the native, or natural flora of the place to which they were introduced. This is an example of how human interaction with nature can blur the boundary of what is considered nature.

Another category of plant has historically been carved out for weeds. Though the term has fallen into disfavor among

botanists
as a formal way to categorize "useless" plants, the informal use of the word "weeds" to describe those plants that are deemed worthy of elimination is illustrative of the general tendency of people and societies to seek to alter or shape the course of nature. Similarly, animals are often categorized in ways such as domestic, farm animals, wild animals, pests, etc. according to their relationship to human life.

algae. They are also distinguished from plants, algae, and fungi by lacking cell walls
.

With a few exceptions, most notably the

shells, bones, and spicules
, a framework upon which cells can move about and be reorganized during development and maturation, and which supports the complex anatomy required for mobility.

Human interrelationship

She-oak
.
Sochi dendrarium is an example of confluence of "natural" and a "made" environment

Although humans currently comprise only a minuscule proportion of the total living biomass on Earth, the human effect on nature is disproportionately large. Because of the extent of human influence, the boundaries between what humans regard as nature and "made environments" is not clear cut except at the extremes. Even at the extremes, the amount of natural environment that is free of discernible human influence is presently diminishing at an increasingly rapid pace.

The development of technology by the human race has allowed the greater exploitation of natural resources and has helped to alleviate some of the risk from natural hazards. In spite of this progress, however, the fate of human civilization remains closely linked to changes in the environment. There exists a highly complex feedback loop between the use of advanced technology and changes to the environment that are only slowly becoming understood.[66] Man-made threats to the Earth's natural environment include pollution, deforestation, and disasters such as oil spills. Humans have contributed to the extinction of many plants and animals.

Humans employ nature for both leisure and economic activities. The acquisition of natural resources for industrial use remains the primary component of the world's economic system. [

9th millennium BCE. Ranging from food production to energy
, nature influences economic wealth.

Although early humans gathered uncultivated plant materials for food and employed the medicinal properties of vegetation for healing,[67] most modern human use of plants is through agriculture. The clearance of large tracts of land for crop growth has led to a significant reduction in the amount available of forestation and wetlands, resulting in the loss of habitat for many plant and animal species as well as increased erosion.[68]

Aesthetics and beauty

Butterwort

Tang Dynasty (618–907). The tradition of representing nature as it is became one of the aims of Chinese painting
and was a significant influence in Asian art.

Although natural wonders are celebrated in the

Romantic movement. British artists John Constable and J. M. W. Turner turned their attention to capturing the beauty of the natural world in their paintings. Before that, paintings had been primarily of religious scenes or of human beings. William Wordsworth's poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increasingly the valuing of nature became an aspect of Western culture.[70] This artistic movement also coincided with the Transcendentalist movement in the Western world. A common classical idea of beautiful art involves the word mimesis, the imitation of nature. Also in the realm of ideas about beauty in nature is that the perfect is implied through perfect mathematical forms and more generally by patterns in nature. As David Rothenburg writes, "The beautiful is the root of science and the goal of art, the highest possibility that humanity can ever hope to see".[71]
: 281 

Matter and energy

The first few hydrogen atom electron orbitals shown as cross-sections with color-coded probability density
Main articles: Matter and Energy

Some fields of science see nature as matter in motion, obeying certain laws of nature which science seeks to understand. For this reason the most fundamental science is generally understood to be "physics" – the name for which is still recognizable as meaning that it is the study of nature.

Matter is commonly defined as the substance of which physical objects are composed. It constitutes the observable universe. The visible components of the universe are now believed to compose only 4.9 percent of the total mass. The remainder is believed to consist of 26.8 percent cold dark matter and 68.3 percent dark energy.[72] The exact nature of these components is still unknown and is currently under intensive investigation by physicists.

The behavior of matter and energy throughout the observable universe appears to follow well-defined

physical laws. These laws have been employed to produce cosmological models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty physical constants[73] that appear to be static across the observable universe.[74]
The values of these constants have been carefully measured, but the reason for their specific values remains a mystery.

Beyond Earth

Planets and dwarf planets of the Solar System (Sizes to scale, distances not to scale)
light years in diameter and approximately 60 million light years from Earth
Main articles: Outer space, Universe, and Extraterrestrial life

Outer space, also simply called space, refers to the relatively empty regions of the

heliopause
.

Outer space is sparsely filled with several dozen types of

meteors. Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this debris
re-enters the atmosphere periodically.

Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet Mars possessed bodies of liquid water on the surface.[75] For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen. If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.[76]

Conditions on the other terrestrial planets, Mercury and Venus, appear to be too harsh to support life as we know it. [citation needed] But it has been conjectured that Europa, the fourth-largest moon of Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.[77]

Nowadays, astronomers started to discover extrasolar Earth analogs – planets that lie in the habitable zone of space surrounding a star, and therefore could possibly host life as we know it.[78]

See also

Media:

Organizations:

Science:

Philosophy:

Notes and references

  1. ^ Harper, Douglas. "nature". Online Etymology Dictionary. Retrieved 2006-09-23.
  2. ^ A useful though somewhat erratically presented account of the pre-Socratic use of the concept of φύσις may be found in Naddaf, Gerard The Greek Concept of Nature, SUNY Press, 2006. The word φύσις, while first used in connection with a plant in Homer, occurs very early in Greek philosophy, and in several senses. Generally, these senses match rather well the current senses in which the English word nature is used, as confirmed by Guthrie, W.K.C. Presocratic Tradition from Parmenides to Democritus (volume 2 of his History of Greek Philosophy), Cambridge UP, 1965.
  3. ^ The first known use of physis was by Homer in reference to the intrinsic qualities of a plant: ὣς ἄρα φωνήσας πόρε φάρμακον ἀργεϊφόντης ἐκ γαίης ἐρύσας, καί μοι φύσιν αὐτοῦ ἔδειξε. (So saying, Argeiphontes [=Hermes] gave me the herb, drawing it from the ground, and showed me its nature.) Odyssey 10.302-3 (ed. A.T. Murray). (The word is dealt with thoroughly in Liddell and Scott's Greek Lexicon.) For later but still very early Greek uses of the term, see earlier note.
  4. Philosophiae Naturalis Principia Mathematica (1687), for example, is translated "Mathematical Principles of Natural Philosophy", and reflects the then-current use of the words "natural philosophy
    ", akin to "systematic study of nature"
  5. ^ The etymology of the word "physical" shows its use as a synonym for "natural" in about the mid-15th century: Harper, Douglas. "physical". Online Etymology Dictionary. Retrieved 2006-09-20.
  6. ^ "World Climates". Blue Planet Biomes. Retrieved 2006-09-21.
  7. ^ "Calculations favor reducing atmosphere for early Earth". Science Daily. 2005-09-11. Retrieved 2007-01-06.
  8. ^ "Past Climate Change". U.S. Environmental Protection Agency. Retrieved 2007-01-07.
  9. ^ Hugh Anderson, Bernard Walter (March 28, 1997). "History of Climate Change". NASA. Archived from the original on 2008-01-23. Retrieved 2007-01-07.
  10. ^ Weart, Spencer (June 2006). "The Discovery of Global Warming". American Institute of Physics. Retrieved 2007-01-07.{{cite web}}: CS1 maint: date and year (link)
  11. ^
    ISBN 0-684-81326-2. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help
    )
  12. ISBN 0-8047-1569-6
    .
  13. ^ Morbidelli, A.; Chambers, J.; Lunine, J. I.; Petit, J. M.; Robert, F.; Valsecchi, G. B.; Cyr, K. E. (2000). "Source Regions and Time Scales for the Delivery of Water to Earth". Meteoritics & Planetary Science. 35 (6): 1309–1320.
    S2CID 129817341
    .
  14. ^ "Earth's Oldest Mineral Grains Suggest an Early Start for Life". NASA Astrobiology Institute. 2001-12-24. Retrieved 2006-05-24.
  15. doi:10.1511/2004.4.324. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help
    )
  16. ISBN 0-521-36615-1. {{cite book}}: |editor= has generic name (help
    )
  17. S2CID 43002817.{{cite journal}}: CS1 maint: date and year (link
    )
  18. ISBN 0-684-81326-2. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help
    )
  19. PMID 2574887
    .
  20. PMID 11344295
    .
  21. S2CID 52953180
    .
  22. ^ See, e.g. [1], [2], [3]
  23. ^ "Ideal Gases under Constant Volume, Constant Pressure, Constant Temperature, & Adiabatic Conditions". NASA. Retrieved 2007-01-07.
  24. PMID 11875208
    .
  25. ^ "Tropical Ocean Warming Drives Recent Northern Hemisphere Climate Change". Science Daily. April 6, 2001. Retrieved 2006-05-24.
  26. ^ "Water for Life". Un.org. 2005-03-22. Retrieved 2011-05-14.
  27. ^ "World". CIA - The world fact book. Retrieved 2008-12-20.
  28. ^ Water Vapor in the Climate System, Special Report, American Geophysical Union, December 1995.
  29. UNEP
    .
  30. ^ "Ocean". The Columbia Encyclopedia. 2002. New York: Columbia University Press
  31. ^ "Distribution of land and water on the planet". UN Atlas of the Oceans
  32. ^ Spilhaus, Athelstan F. 1942 (Jul.). "Maps of the whole world ocean." Geographical Review (American Geographical Society). Vol. 32 (3): pp. 431–5.
  33. ^ Brittanica online. "Lake (physical feature)". Retrieved 2008-06-25. [a Lake is] any relatively large body of slowly moving or standing water that occupies an inland basin of appreciable size. Definitions that precisely distinguish lakes, ponds, swamps, and even rivers and other bodies of nonoceanic water are not well established. It may be said, however, that rivers and streams are relatively fast moving; marshes and swamps contain relatively large quantities of grasses, trees, or shrubs; and ponds are relatively small in comparison to lakes. Geologically defined, lakes are temporary bodies of water.
  34. ^ a body of fresh or salt water of considerable size, surrounded by land. "Dictionary.com definition". Retrieved 2008-06-25. {{cite web}}: Check |url= value (help)
  35. ^ River {definition} from Merriam-Webster. Accessed February 2010.
  36. ^ River[dead link], Wordnet
  37. peak; lake and pond; or river and creek
    ?
  38. S2CID 6894397
    .
  39. ^ Pidwirny, Michael (2006). "Introduction to the Biosphere: Introduction to the Ecosystem Concept". Fundamentals of Physical Geography (2nd Edition). Retrieved September 28, 2006.
  40. ^ Odum, EP (1971) Fundamentals of ecology, third edition, Saunders New York
  41. ^ Pidwirny, Michael (2006). "Introduction to the Biosphere: Organization of Life". Fundamentals of Physical Geography (2nd Edition). Retrieved September 28, 2006.
  42. S2CID 31998098.{{cite journal}}: CS1 maint: date and year (link
    )
  43. ISBN 1559634650
    .
  44. ^ "Definition of Life". California Academy of Sciences. 2006. Retrieved 2007-01-07.
  45. ISBN 0-88936-882-1., which takes global average weight as 60 kg.), the total human biomass is the average weight multiplied by the current human population of approximately 6.5 billion (see, e.g., "World Population Information". U.S. Census Bureau. Retrieved September 28, 2006.): Assuming 60–70 kg to be the average human mass (approximately 130–150 lb on the average), an approximation of total global human mass of between 390 billion (390×109) and 455 billion kg (between 845 billion and 975 billion lb, or about 423 million–488 million short tons
    ). The total biomass of all kinds on earth is estimated to be in excess of 6.8 x 1013 kg (75 billion short tons). By these calculations, the portion of total biomass accounted for by humans would be very roughly 0.6%.
  46. ^ Sengbusch, Peter V. "The Flow of Energy in Ecosystems – Productivity, Food Chain, and Trophic Level". Botany online. University of Hamburg Department of Biology. Retrieved September 23, 2006.
  47. ^ Pidwirny, Michael (2006). "Introduction to the Biosphere: Species Diversity and Biodiversity". Fundamentals of Physical Geography (2nd Edition). Retrieved September 23, 2006.
  48. ^ "How Many Species are There?". Extinction Web Page Class Notes. Retrieved September 23, 2006.
  49. ^ "Animal." World Book Encyclopedia. 16 vols. Chicago: World Book, 2003. This source gives an estimate of from 2 to 50 million.
  50. ^ "Just How Many Species Are There, Anyway?". Science Daily. May 2003. Retrieved September 26, 2006.{{cite web}}: CS1 maint: date and year (link)
  51. ^ Withers, Mark A. (1998). "Changing Patterns in the Number of Species in North American Floras". Land Use History of North America. Retrieved September 26, 2006. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Website based on the contents of the book: Sisk, T.D., ed., ed. (1998). Perspectives on the land use history of North America: a context for understanding our changing environment (Revised September 1999 ed.). U.S. Geological Survey, Biological Resources Division. USGS/BRD/BSR-1998-0003. {{cite book}}: |editor= has generic name (help)CS1 maint: multiple names: editors list (link)
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External links

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