Not to be confused with: err — be mistaken or incorrect; to go astray morally; sin; transgress: To err is human. A colorless, odorless, tasteless, gaseous mixture, mainly nitrogen approximately 78 percent and oxygen approximately 21 percent with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases. This mixture with varying amounts of moisture and particulate matter, enveloping the earth; the atmosphere.
A giant void; nothingness: The money vanished into thin air. Sports A height achieved by a jump or as part of an airborne maneuver, as in skateboarding or snowboarding: getting big air off the halfpipe; had big airs on every run down the course. Aircraft: send troops to Europe by air. Public utterance; vent: gave air to their grievances. The medium of broadcast radio or television: "often ridiculed A manner of behaving that conveys an impression: a leader with an air of conviction. A distinctive quality or appearance; an aura: The messy room had an air of desperation to it.
The general environment or condition, as in attitudes and ideas: growing impatience in the air. See Synonyms at affectation. Music a. A melody or tune, especially in the soprano or tenor range. To expose to the air in order to dry, cool, or freshen; ventilate.
To make known to others; express publicly: aired my complaints. See Synonyms at voice. To broadcast on television or radio: "The ad was submitted to CBS To be broadcast on television or radio: "tidbits that will air on tonight's 6 o'clock news" Terry Ann Knopf. Of or relating to the air or the movement of air: an air tube. Powered by compressed air: an air horn. Of or relating to the broadcast or transmission of radio or television signals.
Imaginary or unreal: "The guy had just hit it big At sea level dry air has a density of 1. Classical Music music a. Individual Sports, other than specified informal Austral the height gained when getting airborne in surfing, snowboarding, etc. Broadcasting off the air not in the act of broadcasting or being broadcast on radio or television.
Broadcasting on the air in the act of broadcasting or being broadcast on radio or television. Astrology modifier astrology of or relating to a group of three signs of the zodiac, Gemini, Libra, and Aquarius.There are notable archaeological excavations in the region that illustrate the prehistoric past of this region. In the Sahara Desert such mountains often stand out in stark relief as topographic heights amidst lowlands covered by sand. Areas of these deep, often intersecting, valleys also contain waterborne clay and silt deposits.
Underground watercourses in some of these valleys continue to provide year-round oasis and seasonal vegetation. The massif contains volcanic features including the extinct caldera of Arakao, Cenozoic lava flows of hawaiite to trachyte composition, volcanic conestuff rings and one of the largest ring dike systems in the world.
Carboniferous sandstone and coal units in the Iullemmeden Basin just to the west of the massif contain uranium mineralisation sourced from the granites of the massif. The climate is classified as Sahellike that of the regions well to its south.
While the mountains are largely bare of vegetation, the dry wadi river valleys known by the Hausa term " Kori " channel and hold rainwater in gueltas stone pools, such as that near the town of Timiacreating oases which provide forage for animals, and in some areas, farming.
Other, vast, areas of the region are entirely devoid of plant life and with their volcanic protrusions and rock fields present an otherworldly appearance. In the vicinity of temporary rivers named korisspecies like Acacia niloticaFaidherbia albida and the palm Hyphaene thebaica coexist with planted date palms Phoenix dactylifera. In comparison, mountainous areas are even less documented.
Tropical tree species less resistant to drought have been described in the highlands, among which the Fabaceae Acacia laeta and Acacia seyal. Recently, this taxon, Olea europaea subsp. Because of their strong geographic isolation within a Saharan matrix, these species have a high conservation value. These peoples were settled in northern oases, to tend the date palm plantations held by the noble clans.
Agriculture products from oases such as TimiaAouderas and Tabelot are traditionally exchanged against clothes, or salt, brought by camel caravans Azalai from the remote Tenere oases of Bilma and Fachi to the east. During the Neolithic Subpluvial the region was a pastoral area, as is illustrated by images of cattle and large mammals. During the 3rd millennium BC, however, a process of desertification began and the Tuareg from further north migrated into the region. Later art indicated war, depicting horses and chariots.
In particular, a five-meter-high carving of a giraffe at Dabous discovered in is internationally famous. Cave art in the region is predominantly stone carvinginitially with sharp rock, and from around BC perhaps with metal. Successive Tuareg Tel s have controlled the area since at least the twelfth century. Agadez, as well as In-Gall to the east, were the farthest outposts of the Songhai Empire in the early 15th century.Air is the Earth 's atmosphere.
Air around us is a mixture of many gases and dust particles. It is the clear gas in which living things live and breathe. It has an indefinite shape and volume. It has no colour or smell. It has mass and weightbecause it is matter. The weight of air creates atmospheric pressure. There is no air in outer space. Animals live and need to breathe the oxygen in the air.
In breathingthe lungs put oxygen into the bloodand send back carbon dioxide to the air. Plants need the carbon dioxide in the air to live. They give off the oxygen that we breathe. Without it we die of asphyxia. Wind is moving air. This causes weather. Air can be polluted by some gases such as carbon monoxidesmokeand ash. This air pollution causes various problems including smogacid rain and global warming. It can damage people's health. Aircraft use propellers to move air over a wingwhich allows them to fly.
Pneumatics use air pressure to move things. Air cannot be seen by the eye. From Wikipedia, the free encyclopedia. Air is one of the four classical elements — airwaterearthand fire. The English used in this article or section may not be easy for everybody to understand.
You can help Wikipedia by reading Wikipedia:How to write Simple English pagesthen simplifying the article. February New York Times. This short article about physics can be made longer. You can help Wikipedia by adding to it. Categories : Basic English words Physics Atmosphere. Hidden categories: Pages needing to be simplified from February All pages that need simplifying Physics stubs.
See more words from the same century Thesaurus Entries near air aimless aimlessly aims air air base airbase air bases. Accessed 19 Apr. Please tell us where you read or heard it including the quote, if possible.
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Come look at pictures of baby animals. Can you correctly identify these flowers? Can you spell these 10 commonly misspelled words? Do you know the person or title these quotes describe? Login or Register. Thesaurus air noun. Save Word. Log In. Choose the Right Synonym for air Noun poseairairsaffectationmannerism mean an adopted way of speaking or behaving.
Keep scrolling for more. Learn More about air. Share air Post more words for air to Facebook Share more words for air on Twitter. Time Traveler for air The first known use of air was in the 14th century See more words from the same century. Thesaurus Entries near air aimless aimlessly aims air air base airbase air bases See More Nearby Entries. Phrases Related to air air raid castle in the air give air to hot air open air up in the air. Comments on air What made you want to look up air?
Get Word of the Day daily email! Test Your Vocabulary. Love words?And Air Force assessors are the first to say such imaging never tells the whole story. Sprawled on chaise lounges with their knees high in the air and their legs spread wide.
That apparently includes some members of the management of the air port itself and some air traffic controllers.AIR - Moon Safari (Official Video)
In other words, the Air Force is saying that its drone force has been stretched to its limits. One bolt struck near with a tremendous shock and the air was driven in violent waves into the very mouth of the cave.
The climate of Cumberland does not overpower one—the air is of a quality that urges you on to think and do. His eye-glass gave him an air of full dress even at this early hour.
Though late in the afternoon, the sun was hot, the air sultry. In addition to the idiom beginning with air. Advertisement top definitions quizzes related content examples explore dictionary british medical scientific idioms and phrases air 1. Also ayre. Take this quiz on the Words of the Day from April 6—12 to find out!
Idioms for air clear the airto eliminate dissension, ambiguity, or tension from a discussion, situation, etc. See manner 1. Origin of air 2 see origin at ere. About 30, sq. Also called Asben. Words related to air breathbreezewindatmospheretonemoodeffectauraflavorfeelingqualitylookopencirculatediscloserevealcommunicatepublishdeclarebroadcast. Example sentences from the Web for air And Air Force assessors are the first to say such imaging never tells the whole story. The Shadowy U. Exclusive: U.
The Keepers of the Trail Joseph A. Walter and the Wireless Sara Ware Bassett. At sea level dry air has a density of 1.The atmosphere of Earth is the layer of gasescommonly known as airthat surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surfaceabsorbing ultraviolet solar radiationwarming the surface through heat retention greenhouse effectand reducing temperature extremes between day and night the diurnal temperature variation.
By volume, dry air contains Air composition, temperature, and atmospheric pressure vary with altitude, and air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere and in artificial atmospheres. The atmosphere has a mass of about 5. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space.
Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. The study of Earth's atmosphere and its processes is called atmospheric science aerology. The three major constituents of Earth's atmosphere are nitrogenoxygenand argon. Water vapor accounts for roughly 0. Besides argon, already mentioned, other noble gasesneon, helium, krypton, and xenon are also present.
Filtered air includes trace amounts of many other chemical compounds. Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample, including dust of mineral and organic composition, pollen and sporessea sprayand volcanic ash.
Various industrial pollutants also may be present as gases or aerosols, such as chlorine elemental or in compoundsfluorine compounds and elemental mercury vapor. Sulfur compounds such as hydrogen sulfide and sulfur dioxide SO 2 may be derived from natural sources or from industrial air pollution. The average molecular weight of dry air, which can be used to calculate densities or to convert between mole fraction and mass fraction, is about This is decreased when the air is humid.
In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions see the temperature section, below. In this way, Earth's atmosphere can be divided called atmospheric stratification into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere.
The exosphere is the outermost layer of Earth's atmosphere i. This layer is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen and carbon dioxide closer to the exobase. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another.
Thus, the exosphere no longer behaves like a gas, and the particles constantly escape into space. These free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind. The exosphere is located too far above Earth for any meteorological phenomena to be possible. However, the aurora borealis and aurora australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere.
The exosphere contains most of the satellites orbiting Earth. The thermosphere is the second-highest layer of Earth's atmosphere. The height of the thermopause varies considerably due to changes in solar activity.The mixture contains a group of gases of nearly constant concentrations and a group with concentrations that are variable in both space and time. The atmospheric gases of steady concentration and their proportions in percentage by volume are as follows:.
The uniformity of composition is maintained by mixing associated with atmospheric motions; but, above a height of about 90 km 55 milesdiffusional processes become more important than mixing, and the lighter gases hydrogen and helium, in particular are more abundant above that level.
Of the gases present in variable concentrations, water vapourozonecarbon dioxide, sulfur dioxideand nitrogen dioxide are of principal importance. The typical concentration ranges of these gases in percentage by volume are as follows:. Water vapour is the source for all forms of precipitation and is an important absorber and emitter of infrared radiation.
Carbon dioxidebesides being involved in the process of photosynthesisis also an important absorber and emitter of infrared radiation.
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Air atmospheric gas. See Article History. Read More on This Topic. For modern atmospheric chemistry and physics, see atmosphere. Get exclusive access to content from our First Edition with your subscription. Subscribe today. Learn More in these related Britannica articles:. In a manner analogous to the treatment of standing waves in a stretched string, it is possible to carry out an analysis of the structure of standing waves in air columns.
If two identical sinusoidal waves move in opposite directions in a column…. All forms of precipitation, including drizzle, rain, snow, ice crystals, and hail, are produced as a result of the condensation of atmospheric moisture that forms clouds in which some….
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