air

the atmosphere: The air is fresher in the mountains.; expose: air grievances; a tune: She hummed an air.
Not to be confused with:err – be mistaken or incorrect; to go astray morally; sin; transgress: To err is human.heir – one who inherits an estate: Her nephew is her only heir.

air

E0047400 (âr)n.1. a. 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.b. This mixture with varying amounts of moisture and particulate matter, enveloping the earth; the atmosphere.2. a. The sky; the firmament.b. A giant void; nothingness: The money vanished into thin air.3. An atmospheric movement; a breeze or wind.4. 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.5. Aircraft: send troops to Europe by air.6. a. Public utterance; vent: gave air to their grievances.b. The medium of broadcast radio or television: "often ridiculed ... extremist groups on air" (Christian Science Monitor).7. a. A manner of behaving that conveys an impression: a leader with an air of conviction.b. A distinctive quality or appearance; an aura: The messy room had an air of desperation to it.c. The general environment or condition, as in attitudes and ideas: growing impatience in the air.d. airs Affected behavior; affectation: put on airs. See Synonyms at affectation.8. Music a. A melody or tune, especially in the soprano or tenor range.b. A solo with or without accompaniment.9. Air conditioning.10. Archaic Breath.v. aired, air·ing, airs v.tr.1. To expose to the air in order to dry, cool, or freshen; ventilate.2. To make known to others; express publicly: aired my complaints. See Synonyms at voice.3. To broadcast on television or radio: "The ad was submitted to CBS ... which accepted and aired it" (New York).v.intr. To be broadcast on television or radio: "tidbits that will air on tonight's 6 o'clock news" (Terry Ann Knopf).adj.1. Of or relating to the air or the movement of air: an air tube.2. Existing or living in the air; aerial.3. Powered by compressed air: an air horn.4. Containing or inflated by air.5. Of or relating to aircraft or aeronautics.6. Of or relating to the broadcast or transmission of radio or television signals.7. Imaginary or unreal: "The guy had just hit it big ... after ten years of eating air sandwiches" (Jonathan Kellerman).Idioms: air one out Football To throw a long pass. in the air Abroad; prevalent: Excitement was in the air. up in the air Not yet decided; uncertain.

[Partly from Middle English air, gas, atmosphere (from Old French, from Latin āēr, from Greek; see wer- in Indo-European roots) and partly from French air, nature, quality, place of origin (from Latin ager, place, field; see agriculture, and Latin ārea, open space, threshing floor; see area). N., sense 8, from French air, tune, from Italian aria; see aria.]

air

(ɛə) n1. (Elements & Compounds) the mixture of gases that forms the earth's atmosphere. At sea level dry air has a density of 1.226 kilograms per cubic metre and consists of 78.08 per cent nitrogen, 20.95 per cent oxygen, 0.93 per cent argon, 0.03 per cent carbon dioxide, with smaller quantities of ozone and inert gases; water vapour varies between 0 and 4 per cent and in industrial areas sulphur gases may be present as pollutants2. the space above and around the earth; sky. 3. breeze; slight wind4. public expression; utterance: to give air to one's complaints. 5. a distinctive quality: an air of mystery. 6. a person's distinctive appearance, manner, or bearing7. (Classical Music) music a. a simple tune for either vocal or instrumental performanceb. another word for aria8. transportation in aircraft (esp in the phrase by air)9. an archaic word for breath¹, breath², breath³10. (Individual Sports, other than specified) informal Austral the height gained when getting airborne in surfing, snowboarding, etc11. clear the air to rid a situation of tension or discord by settling misunderstandings, etc12. give someone the air slang to reject or dismiss someone13. in the air a. in circulation; currentb. in the process of being decided; unsettled14. into thin air leaving no trace behind15. (Broadcasting) off the air not in the act of broadcasting or being broadcast on radio or television16. (Broadcasting) on the air in the act of broadcasting or being broadcast on radio or television17. out of thin air from thin air suddenly and unexpectedly18. take the air to go out of doors, as for a short walk or ride19. up in the air a. uncertainb. informal agitated or excited20. walk on air to feel elated or exhilarated21. (Astrology) (modifier) astrology of or relating to a group of three signs of the zodiac, Gemini, Libra, and Aquarius. Compare earth¹⁰, fire²⁴, water¹²vb22. to expose or be exposed to the air so as to cool or freshen; ventilate: to air a room. 23. to expose or be exposed to warm or heated air so as to dry: to air linen. 24. (tr) to make known publicly; display; publicize: to air one's opinions. 25. (Broadcasting) (intr) (of a television or radio programme) to be broadcast[C13: via Old French and Latin from Greek aēr the lower atmosphere]

AIR

abbreviation for (Broadcasting) All India Radio

Aïr

(ˈɑːɪə) n (Placename) a mountainous region of N central Niger, in the Sahara, rising to 1500 m (5000 ft): a former native kingdom. Area: about 77 700 sq km (30 000 sq miles). Also called: Azbine or Asben

air

(ɛər)

n. 1. a mixture of nitrogen, oxygen, and minute amounts of other gases that surrounds the earth and forms its atmosphere. 2. a stir in the atmosphere; a light breeze. 3. overhead space; sky. 4. circulation; publication; publicity: to give air to one's theories. 5. general character or appearance; aura: an air of mystery about him. 6. airs, affected or unnatural manner; assumed haughtiness. 7. a. a tune; melody. b. an Elizabethan accompanied song. 8. aircraft as a means of transportation: to ship by air. 9. the medium through which radio waves are transmitted. 10. Informal. air conditioning or an air-conditioning system. 11. Archaic. breath. v.t. 12. to expose to the air; ventilate (often fol. by out). 13. to bring to public notice; display: to air one's opinions. 14. to broadcast or televise. v.i. 15. to be exposed to the open air (often fol. by out): Let the room air out. 16. to be broadcast or televised. adj. 17. operating by means of air pressure or by acting upon air: an air drill; an air pump. 18. of or pertaining to aircraft or to aviation. 19. taking place in the air; aerial. 20. imaginary; imitated; mimicked (used before the name of a musical instrument): to play the air guitar. Idioms: 1. clear the air, to eliminate misunderstandings. 2. give someone the air, to reject someone, as a lover. 3. in the air, in circulation; current: an interesting rumor in the air. 4. into thin air, so as to disappear completely. 5. off the air, not broadcasting or being broadcast. 6. on the air, broadcasting or being broadcast. 7. up in the air, not decided; unsettled. 8. walk or tread on air, to feel elated. [1150–1200; Middle English eir < Old French air < Latin āēr- < Greek āḗr] syn: See wind¹.

a-i-r

artist-in-residence.

air

(âr) The colorless, odorless, tasteless mixture of gases that surrounds the Earth. Air contains about 78 percent nitrogen and 21 percent oxygen, with the remaining part being made up of argon, carbon dioxide, neon, helium, and other gases.

air

- An expressive succession of musical sounds—a melody or tune.See also related terms for melody.

air

In artillery and naval gunfire support, a spotting, or an observation, by a spotter or an observer to indicate that a burst or group of bursts occurred before impact.

Air

air

Past participle: aired
Gerund: airing

Imperative
air
air

Present
I air
you air
he/she/it airs
we air
you air
they air

Preterite
I aired
you aired
he/she/it aired
we aired
you aired
they aired

Present Continuous
I am airing
you are airing
he/she/it is airing
we are airing
you are airing
they are airing

Present Perfect
I have aired
you have aired
he/she/it has aired
we have aired
you have aired
they have aired

Past Continuous
I was airing
you were airing
he/she/it was airing
we were airing
you were airing
they were airing

Past Perfect
I had aired
you had aired
he/she/it had aired
we had aired
you had aired
they had aired

Future
I will air
you will air
he/she/it will air
we will air
you will air
they will air

Future Perfect
I will have aired
you will have aired
he/she/it will have aired
we will have aired
you will have aired
they will have aired

Future Continuous
I will be airing
you will be airing
he/she/it will be airing
we will be airing
you will be airing
they will be airing

Present Perfect Continuous
I have been airing
you have been airing
he/she/it has been airing
we have been airing
you have been airing
they have been airing

Future Perfect Continuous
I will have been airing
you will have been airing
he/she/it will have been airing
we will have been airing
you will have been airing
they will have been airing

Past Perfect Continuous
I had been airing
you had been airing
he/she/it had been airing
we had been airing
you had been airing
they had been airing

Conditional
I would air
you would air
he/she/it would air
we would air
you would air
they would air

Past Conditional
I would have aired
you would have aired
he/she/it would have aired
we would have aired
you would have aired
they would have aired

air

One of the four elements; associated with the intellect and thought.

Thesaurus

Noun	1.	air - a mixture of gases (especially oxygen) required for breathing; the stuff that the wind consists of; "air pollution"; "a smell of chemicals in the air"; "open a window and let in some air"; "I need some fresh air"air current, current of air, wind - air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure; "trees bent under the fierce winds"; "when there is no wind, row"; "the radioactivity was being swept upwards by the air current and out into the atmosphere"Ar, argon, atomic number 18 - a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphereatomic number 36, Kr, krypton - a colorless element that is one of the six inert gasses; occurs in trace amounts in airatomic number 10, Ne, neon - a colorless odorless gaseous element that give a red glow in a vacuum tube; one of the six inert gasses; occurs in the air in small amountsatomic number 7, N, nitrogen - a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissuesatomic number 8, O, oxygen - a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crustatomic number 54, Xe, xenon - a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amountsbreath - the air that is inhaled and exhaled in respiration; "his sour breath offended her"hot air - air that has been heated and tends to risegas - a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitelyliquid air - air in a liquid state
	2.	air - the region above the ground; "her hand stopped in mid air"; "he threw the ball into the air"region, part - the extended spatial location of something; "the farming regions of France"; "religions in all parts of the world"; "regions of outer space"
	3.	air - a distinctive but intangible quality surrounding a person or thing; "an air of mystery"; "the house had a neglected air"; "an atmosphere of defeat pervaded the candidate's headquarters"; "the place had an aura of romance"aura, atmospherequality - an essential and distinguishing attribute of something or someone; "the quality of mercy is not strained"--Shakespearemystique - an aura of heightened value or interest or meaning surrounding a person or thingnote - a characteristic emotional quality; "it ended on a sour note"; "there was a note of gaiety in her manner"; "he detected a note of sarcasm"vibe, vibration - a distinctive emotional aura experienced instinctively; "that place gave me bad vibrations"; "it gave me a nostalgic vibe"
	4.	air - a slight wind (usually refreshing); "the breeze was cooled by the lake"; "as he waited he could feel the air on his neck"breeze, gentle wind, zephyrsea breeze - a cooling breeze from the sea (during the daytime)breath - a slight movement of the air; "there wasn't a breath of air in the room"light air - wind moving 1-3 knots; 1 on the Beaufort scalelight breeze - wind moving 4-7 knots; 2 on the Beaufort scalegentle breeze - wind moving 8-12 knots; 3 on the Beaufort scalemoderate breeze - wind moving 13-18 knots; 4 on the Beaufort scalefresh breeze - wind moving 19-24 knots; 5 on the Beaufort scalestrong breeze - wind moving 25-31 knots; 6 on the Beaufort scaleair current, current of air, wind - air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure; "trees bent under the fierce winds"; "when there is no wind, row"; "the radioactivity was being swept upwards by the air current and out into the atmosphere"
	5.	air - the mass of air surrounding the Earth; "there was great heat as the comet entered the atmosphere"; "it was exposed to the air"atmosphereairspace - the atmosphere above a nation that is deemed to be under its jurisdiction; "the plane was refused permission to enter Chinese airspace"air space, airspace - the space in the atmosphere immediately above the earthionosphere - the outer region of the Earth's atmosphere; contains a high concentration of free electronsregion, part - the extended spatial location of something; "the farming regions of France"; "religions in all parts of the world"; "regions of outer space"earth, globe, world - the 3rd planet from the sun; the planet we live on; "the Earth moves around the sun"; "he sailed around the world"
	6.	air - once thought to be one of four elements composing the universe (Empedocles)archaicism, archaism - the use of an archaic expressionelement - one of four substances thought in ancient and medieval cosmology to constitute the physical universe; "the alchemists believed that there were four elements"
	7.	air - a succession of notes forming a distinctive sequence; "she was humming an air from Beethoven"melodic line, melodic phrase, melody, tune, strain, linetucket, fanfare, flourish - (music) a short lively tune played on brass instruments; "he entered to a flourish of trumpets"; "her arrival was greeted with a rousing fanfare"glissando - a rapid series of ascending or descending notes on the musical scaleroulade - (music) an elaborate run of several notes sung to one syllablemusic - an artistic form of auditory communication incorporating instrumental or vocal tones in a structured and continuous mannerleitmotif, leitmotiv - a melodic phrase that accompanies the reappearance of a person or situation (as in Wagner's operas)theme song - a melody that recurs and comes to represent a musical play or moviesignature tune, theme song, signature - a melody used to identify a performer or a dance band or radio/tv programmelodic theme, musical theme, theme, idea - (music) melodic subject of a musical composition; "the theme is announced in the first measures"; "the accompanist picked up the idea and elaborated it"part, voice - the melody carried by a particular voice or instrument in polyphonic music; "he tried to sing the tenor part"musical phrase, phrase - a short musical passage
	8.	air - medium for radio and television broadcasting; "the program was on the air from 9 til midnight"; "the president used the airwaves to take his message to the people"airwavemedium - an intervening substance through which signals can travel as a means for communication
	9.	air - travel via aircraft; "air travel involves too much waiting in airports"; "if you've time to spare go by air"air travel, aviationtravel, traveling, travelling - the act of going from one place to another; "he enjoyed selling but he hated the travel"flying, flight - an instance of traveling by air; "flying was still an exciting adventure for him"overfly, pass over - fly over; "The plane passed over Damascus"fly - travel in an airplane; "she is flying to Cincinnati tonight"; "Are we driving or flying?"red-eye - travel on an overnight flight; "The candidate red-eyed from California to the East Coast the night before the election to give a last stump speech"cruise - travel at a moderate speed; "Please keep your seat belt fastened while the plane is reaching cruising altitude"stooge - cruise in slow or routine flightsstall - cause an airplane to go into a stallstall - experience a stall in flight, of airplanesbuzz - fly low; "Planes buzzed the crowds in the square"crab - direct (an aircraft) into a crosswindaviate, pilot, fly - operate an airplane; "The pilot flew to Cuba"fly blind - fly an airplane solely by relying on instrumentsfly contact - fly a plane by using visible landmarks or points of referencesolo - fly alone, without a co-pilot or passengerstest fly - test a planejet - fly a jet planeglide - fly in or as if in a glider planekite - soar or fly like a kite; "The pilot kited for a long time over the mountains"sailplane, soar - fly a plane without an enginepower-dive - make a power dive; "The airplane power-dived"nosedive - plunge nose first; drop with the nose or front first, of aircraftcrash-dive - descend steeply and rapidlychandelle - climb suddenly and steeply; "The airplane chandelled"belly-land - land on the underside without the landing gearcrash land - make an emergency landingditch - make an emergency landing on waterland, put down, bring down - cause to come to the ground; "the pilot managed to land the airplane safely"deplane - get off an airplaneemplane, enplane - board a planepeel off - leave a formation
Verb	1.	air - expose to fresh air; "aerate your old sneakers"aerate, air outexpose - expose or make accessible to some action or influence; "Expose your students to art"; "expose the blanket to sunshine"
	2.	air - be broadcast; "This show will air Saturdays at 2 P.M."broadcast medium, broadcasting - a medium that disseminates via telecommunicationsbe on, get on - appear in a show, on T.V. or radio; "The news won't be on tonight"
	3.	air - broadcast over the airwaves, as in radio or television; "We cannot air this X-rated song"broadcast, transmit, beam, sendbroadcast medium, broadcasting - a medium that disseminates via telecommunicationspublicize, bare, publicise, air - make public; "She aired her opinions on welfare"satellite - broadcast or disseminate via satellitesportscast - broadcast a sports eventtelecast, televise - broadcast via television; "The Royal wedding was televised"interrogate - transmit (a signal) for setting off an appropriate response, as in telecommunicationrebroadcast, rerun - broadcast again, as of a film
	4.	air - make public; "She aired her opinions on welfare"publicize, bare, publicisetell - let something be known; "Tell them that you will be late"hype - publicize in an exaggerated and often misleading mannerbulletin - make public by bulletinissue, publish, bring out, release, put out - prepare and issue for public distribution or sale; "publish a magazine or newspaper"disseminate, pass around, circulate, diffuse, broadcast, circularise, circularize, spread, disperse, propagate, distribute - cause to become widely known; "spread information"; "circulate a rumor"; "broadcast the news"broadcast, air, transmit, beam, send - broadcast over the airwaves, as in radio or television; "We cannot air this X-rated song"
	5.	air - expose to warm or heated air, so as to dry; "Air linen"dry, dry out - remove the moisture from and make dry; "dry clothes"; "dry hair"
	6.	air - expose to cool or cold air so as to cool or freshen; "air the old winter clothes"; "air out the smoke-filled rooms"ventilate, air out, ventfreshen, refresh - make (to feel) fresh; "The cool water refreshed us"

air

noun1. wind, blast, breath, breeze, puff, whiff, draught, gust, waft, zephyr, air-current, current of air Draughts help to circulate air.2. atmosphere, sky, heavens, aerosphere They fired their guns in the air.3. tune, song, theme, melody, strain, lay, aria an old Irish air4. manner, feeling, effect, style, quality, character, bearing, appearance, look, aspect, atmosphere, tone, mood, impression, flavour, aura, ambience, demeanour, vibe (slang) The meal gave the occasion an almost festive air.plural noun1. affectation, arrogance, pretensions, pomposity, swank (informal), hauteur, haughtiness, superciliousness, affectedness We're poor and we never put on airs.verb1. broadcast, show, cable, beam, transmit, relay, televise, put on the air Tonight, the channel will air a documentary called 'Democracy in Action'.2. publicize, tell, reveal, exhibit, communicate, voice, express, display, declare, expose, disclose, proclaim, utter, circulate, make public, divulge, disseminate, ventilate, make known, give vent to, take the wraps off The whole issue was thoroughly aired at the meeting3. ventilate, expose, freshen, aerate Once a week she cleaned and aired each room.up in the air uncertain, vague, unclear, doubtful, dubious, unsettled, unsure, unresolved, in the balance, undecided, hazy, unconfirmed, vacillating, undetermined, unfixed The President's trip is still very much up in the air.walking on air ecstatic, entranced, joyous, enthusiastic, frenzied, fervent, joyful, elated, over the moon (informal), overjoyed, transported, blissful, delirious, euphoric, rapturous, enraptured, on cloud nine (informal), cock-a-hoop, blissed out, rhapsodic, in seventh heaven, floating on air, in exaltation, in transports of delight As soon as I got the news I was walking on air.Related words
adjective aerial
fear aerophobiaProverbs
"Fresh air keeps the doctor poor"

air

noun1. The gaseous mixture enveloping the earth:atmosphere.2. The celestial regions as seen from the earth:firmament, heaven (often used in plural), sky.Archaic: welkin.3. A natural movement or current of air:blast, blow, breeze, gust, wind, zephyr.Archaic: gale.4. A general impression produced by a predominant quality or characteristic:ambiance, atmosphere, aura, feel, feeling, mood, smell, tone.5. Behavior through which one reveals one's personality:address, bearing, demeanor, manner, mien, presence, style.Archaic: port.6. Artificial behavior adopted to impress others.Used in plural:affectation, affectedness, mannerism, pose, pretense.7. A pleasing succession of musical tones forming a usually brief aesthetic unit:aria, melody, strain, tune.Obsolete: note.verb1. To expose to circulating air:aerate, ventilate, wind.2. To utter publicly:express, put, state, vent, ventilate.Idiom: come out with.

Translations

使公開外觀天空晾晒曲調

air

(eə) noun1. the mixture of gases we breathe; the atmosphere. Mountain air is pure.空氣2. the space above the ground; the sky. Birds fly through the air.天空3. appearance. The house had an air of neglect.外觀4. a tune. She played a simple air on the piano.曲調 verb1. to expose to the air in order to dry or make more fresh etc. to air linen.晾晒2. to make known. He loved to air his opinions.使公開ˈairbag noun a safety bag in a car that protects the driver or a passenger in an accident. 安全气袋ˈairily adverb in a light-hearted manner. She airily dismissed all objections. 活潑地，轻率地 ˈairiness noun通風ˈairing noun a short walk etc in the open air. She took the baby for an airing. 戶外散步，兜风 ˈairless adjective1. (of weather) still and windless. It was a hot, airless night.無風的2. (of a room etc) stuffy and without fresh air. 不通風的ˈairy adjective1. with plenty of (fresh) air. an airy room. 通风的，空气新鲜的 2. light-hearted and not serious. an airy disregard for authority.輕率的ˈairborne adjective in the air or flying. We were airborne five minutes after boarding the plane; airborne germs. 在空中的，空运的，空气传播的 ˌair-conˈditioned adjective having air-conditioning. an air-conditioned building.有空調的ˌair-conˈditioner noun an apparatus providing air-conditioning. 空調器ˌair-conˈditioning noun a method of providing a room, building etc with air of a controlled temperature and humidity. 空調ˈaircraft – plural ˈaircraft – noun any of several types of machine for flying in the air. Enemy aircraft have been sighted. 航空器，飞机 aircraft carrier a ship which carries aircraft and which aircraft can use for landing and taking off. 航空母艦ˈairfield noun an area of ground (with buildings etc) where (usually military) aircraft are kept and from which they fly. 飛機場air force the part of the armed services which uses aircraft. the army, navy and air force.空軍ˈair-gun noun a gun that is worked by air under pressure. 氣槍air hostess a young woman who looks after passengers in an aircraft. 空中小姐air letter a letter sent by airmail. 航空信ˈairlift noun an operation to move cargo or people, carried out by air. 空運ˈairline noun (a company that owns) a regular air transport service. Which airline are you travelling by? 航空公司，航線 ˈairliner noun a (usually large) aircraft for carrying passengers. 客機ˈair-lock noun a bubble in a pipe which prevents liquid from flowing along it. 氣塞ˈairmail noun a system of carrying mail by air. Send this parcel by airmail; (also adjective) an airmail letter.航空郵件ˈairman noun a member of an air force. 空军士兵，飞行员 ˈair pollution nounAir pollution is caused by smoke, toxic gases etc.空氣污染ˈairplane noun (American) an aeroplane. 飛機ˈairport noun a place where passenger aircraft arrive and depart, with buildings for customs, waiting-rooms etc. 機場ˈair-pump noun a pump for forcing air in or out of something. 氣泵ˈair-raid noun an attack by aircraft. 空襲ˈairship noun an aircraft that is lighter than air and can be steered etc. 飛艇ˈairtight adjective (of a container etc) into or through which air cannot pass. an airtight seal on a bottle. 密封的，不透气的 ˈairway noun a regular course followed by aircraft. 航路on the air broadcasting (regularly) on radio or television. 在播送中put on airs / give oneself airs to behave as if one is better or more important than others. She gives herself such airs that everyone dislikes her.擺架子

air

→ 空气zhCN

Air travel → 乘飞机旅行
Does it have air conditioning? → 车里有没有空调
Could you check the air, please? (US)
Can you check the air, please? (UK) → 请帮我检查轮胎充气状况
Does the room have air conditioning? → 房间里有空调吗？
How long will it take by air? → 航空邮件多久能寄到？
The air conditioning doesn't work → 空调不工作

air

air:

see atmosphereatmosphere
[Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied, the science of
..... Click the link for more information. ; liquid airliquid air,
ordinary air that has been liquefied by compression and cooling to extremely low temperatures (see liquefaction). Its commercial preparation involves purification by washing to remove soluble impurities and by passage over calcium oxide (lime) to remove the carbon
..... Click the link for more information. ; ventilationventilation,
process of supplying fresh air to an enclosed space and removing from it air contaminated by odors, gases, or smoke.

Proper ventilation requires also that there be a movement or circulation of the air within the space and that the temperature and humidity be
..... Click the link for more information. .

air

A system in which air is the heat-carrying medium. See also: Radiant-heated floors

Air

(religion, spiritualism, and occult)

In a magic circle, the four elements—Earth, Air, Fire, and Water—are associated with the four directions of North, East, South, and West.

Air is connected with life—the breath of life—and with the soul in magic and mysticism. Many traditions of Wicca apply Air to the East and further associate it with the color yellow and the elementals known as Sylphs. There are correspondences with communication, consciousness, and the powers of the mind.

In Ritual or Ceremonial Magic, air is associated with Raphael and with the Tarot suit of Swords, with spring, the dawn, and the Hebrew letter Yod.

The elements of Earth, Air, Fire, and Water are assigned to different directions in the Native American Medicine Wheels; those associations vary from tribe to tribe.

A L L H A L L OW ' S E V E see SAMHAIN

Aïr

(also Azbine), a plateau in the southern Sahara, in Niger. It is made up of ancient granites and Quaternary lavas. Its average elevation is 800–900 m, with a maximum of about 1,900 m at an extinct volcano. In the valleys of the wadis there is acacia pricklewood; on the slopes, desert savanna; and on the peaks, bare desert. Livestock—zebu and camel—is raised. In the oases, doom palm, millet, wheat, cotton, and maize are cultivated.

Air

a natural mixture of gases, mainly nitrogen and oxygen, which makes up the earth’s atmosphere. The most important geological processes on the earth’s surface, as well as the formation of weather and climate, take place under the action of air and water. Air is the source of the oxygen that is necessary for normal existence of the overwhelming majority of living organisms. Mankind has long obtained the heat necessary for life and productive activity by burning fuel in air. Air is one of the most important sources of chemical raw materials.

Dry air consists of the following gases (percent by volume): nitrogen (N₂), 78.09; oxygen (O₂), 20.95; argon (Ar), 0.93; and carbon dioxide (CO₂), 0.03. Air contains very small quantities of other inert gases, as well as hydrogen (H₂), ozone (0₃), nitrogen oxides, carbon monoxide (CO), ammonia (NH₃), methane (CH₄), and sulfur dioxide (SO₂). Taking into account the molecular weight of each component and its proportion in the composition of air, it is possible to calculate the mean molecular weight of air as 28.966 (approximately 29). The content of nitrogen, oxygen, and inert gases in air is virtually constant, since a constant concentration of oxygen—and in part nitrogen—is maintained by the plants of the earth. The content of carbon dioxide, nitrogen oxides, and sulfur compounds in air fluctuates substantially; in particular, it increases close to large cities and industrial enterprises. The water content of air is not constant; it may range from 0.00002 percent to 3 percent by volume. A large number of small solid dust particles—from a few million per cu m in clean room air to 100-300 million per cu m in large cities—is always present in air. Such particles often serve as centers for the condensation of atmospheric moisture and cause the formation of fog. Air penetrates the soil, making up 10 to 23-28 percent of its volume. Soil air, because of biological processes in the soil, is substantially different from ordinary air in composition: it contains 78-80 percent O₂, 0.1-20.0 percent N₂, and 0.1-15.0 percent CO₂ by volume.

Historical information. Scientists in ancient times considered air to be one of the elements of which all existing things are composed. Anaximenes of Miletus (sixth century B.C.) called air the basic substance, and Empedocles (fifth century) and Aristotle (fourth century) called it one of the four elements—along with fire, water, and earth—in which all inherent properties of matter are contained.

The notion of air as an independent, individual substance prevailed in science until the end of the 18th century. In 1775-77 the French chemist A. Lavoisier showed that the then recently discovered chemical elements nitrogen and oxygen were components of air. In 1894 the English scientists J. Rayleigh and W. Ramsay discovered another element, argon, in the air; later other inert gases were discovered.

The study of the physical properties of air played a large role in the history of science. The Italian scientist Galileo (1632) found that air is 400 times lighter than water. The Italian scientists V. Viviani and E. Torricelli (1643) discovered the existence of atmospheric pressure and invented the barometer to measure it. The French scientist B. Pascal discovered the decrease in atmospheric pressure with altitude. Studying the relationship between pressure and volume of air, R. Boyle and R. Townley (1662) in England and E. Mariotte (1676) in France discovered the law named after them (the Boyle-Mariotte law); subsequently, as science developed, other gas laws were discovered. It was long impossible to liquefy air and its chief components; they were therefore considered “permanent” gases. The failure of attempts to liquefy air was explained only after D. I. Mendeleev established the concept of critical temperature and pressure (1860). In 1877, using air cooled to below the critical temperature (approximately -140°C) under high pressure, L. P. Cailletet (Paris) and R. Pictet (Geneva) succeeded in converting air to liquid. In 1895 the German engineer C. von Linde designed and built the first industrial establishment for liquefying air.

Physical properties. The air pressure at 0° C and sea level is 101,325 newtons (N) per sq m, which is equal to 1.01325 bars, 1 atmosphere (atm), or 760 mm of mercury (mm Hg); under these conditions the mass of 1 liter (l) of air is 1.2928 g. For most practical purposes, air may be regarded as an ideal gas; in particular, the partial pressure of each component gas does not depend on the presence of the other components of air. The critical temperature is —140.7° C; the critical pressure is 3.7 MN/m² (37.2 atm). The following properties of air are given at a pressure of 101,325 N/m², or 1.01325 bars (so-called standard pressure): specific heat at constant pressure C_p, 10.045 x 10³ joules/(kg - ° K), or 0.24 cal/(g . ° C) in the range of 0°-100° C, and at a constant volume C_v 8.3710 x 10³ joules/(kg . ° K), or 0.2002 cal/(g . ° C) in the range of 0°-1500° C; coefficient of thermal conductivity, 0.024276 watts/(m . ° K), or 0.000058 cal/(cm . sec . ° C), at 0° C, and 0.030136 watts/(m . ° K), or 0.000072 cal/(cm . sec . ° C), at a temperature of 100° C; coefficient of thermal expansion, 0.003670 (0°-100°C); viscosity, 0.0171 (0° C) and 0.0181 (20° C) MN . sec/m² (centipoise); degree of compressibility z = pV/p₀V₀, 1.00060 (0°C), 1.09218 (25° C), or 1.18376 (50° C); index of refraction, 1.00029; dielectric permeability, 1.000059 (0° C); and solubility in water (in cu cm for 1 / of water), 29.18 (0° C) or 18.68 (20° C). Since the solubility of oxygen in water is somewhat higher than that of nitrogen, the ratio between these gases upon solution in water changes and becomes 35 percent and 65 percent respectively. The speed of sound in air at 0° C is approximately 330 m/sec.

Liquid air. Liquid air is bluish liquid with a density of 0.96 g/cm³ (at - 192 ° C and standard pressure). Freely evaporating liquid air at standard pressure has a temperature of approx. -190° C. Its composition is not constant, since nitrogen and argon volatilize more rapidly than oxygen. Fractional evap-oration of liquid air is used to obtain pure nitrogen and oxygen, argon, and other inert gases. Liquid air is stored and transported in Dewar flasks or specially constructed tanks. Compressed air is stored in steel cylinders at 15 MN/m2 (150 atm); the cylinders are black, with the white label “Compressed Air.”

V. L. VASILEVSKII

Physiological and sanitary significance of air. The fluctuations in the nitrogen and oxygen content of atmospheric air are insignificant and do not have a significant effect on the human organism. The percentage composition of air, particularly the partial pressure of oxygen, is important for man’s normal vital activity. The partial pressure of oxygen in the air at sea level is 21,331.5 N/m² (160 mm Hg); the first symptoms of oxygen deficiency, which in healthy persons are readily compensated by increased frequency and depth of respiration, acceleration of blood flow, and an increase in the quantity of erythrocytes, appear when the partial pressure is decreased to 18,665 N/m² (140 mm Hg). With a decrease to 14,665.4 N/m² (110 mm Hg), compensation is insufficient, and symptoms of hypoxia appear; a decrease to 6,666.1-7,999.3 N/m² (50-60 mm Hg) is dangerous to life. An increase in the partial pressure of oxygen all the way to respi-ration of pure oxygen (a partial pressure of 101,325 N/m², or 760 mm Hg) can be tolerated by healthy persons without adverse consequences.

At normal partial pressure, nitrogen is inert. An increase in its partial pressure to 0.8-1.2 MN/m² (8-12 atm) leads to the appearance of narcosis. A significant increase in the content of nitrogen in the air (up to 93 percent and more) as a result of a decrease in the partial pressure of oxygen may lead to anoxemia and even death. The content of carbon dioxide, the physiological stimulant of the breathing center in atmospheric air, is usually 0.03-0.04 percent by volume. A certain increase in its concentration in the air of industrial centers is insignificant to the body. At high carbon-dioxide concentrations and with a decrease in the partial pressure of oxygen, asphyxia may occur. At a carbon-dioxide content of 14-15 percent in the air, death may occur from paralysis of the breathing center. An increase in the concentration of CO₂ in the air in buildings occurs principally because of the respiration and vital activity of people. (An adult at rest at 18°-20° C emits about 20/ of CO₂ per hour.) Therefore, the CO₂ content of air on the one hand, and of organic compounds, microorganisms, and dust on the other, increase simultaneously; the concentration of CO₂ in air in buildings is a sanitary indicator of the cleanliness of the air. The CO₂ content of air in residential premises should not exceed 0.1 percent. The inert gases found in insignificant amounts in atmospheric air—argon, helium, neon, krypton, and xenon—have no effect on the organism at standard pressure. The radioactive gas radon and its isotopes actinon and thoron, which have short half-lives and are observed in atmospheric air in minute concentrations, do not have an unfavorable effect on man.

Various microorganisms (bacteria, fungi, and so on) are ordinarily found in atmospheric air. However, pathogenic microorganisms in the air are extremely rare, as a result of which the transmission of infectious diseases through atmospheric air occurs only in exceptional cases—for example, with the use of bacteriological weapons and in closed areas where there are sick persons who are emitting pathogenic microorganisms into the air with minute droplets of saliva when coughing, sneezing, or speaking. Depending on the resistance of the microorganisms, they may be transmitted through the air by means of droplets, as well as by dust particles—the most resistant microorganisms are the causative agents of tuberculosis and diphtheria.

The temperature, humidity, and movement of the air have great significance for the vital activity of man. The optimal air temperature for an ordinarily dressed person performing light work is 18°-20° C. Heavier work requires a lower air temperature. Thanks to advanced mechanisms of thermal regulation, humans readily tolerate changes in temperature and can adapt to various climatic conditions. The optimal relative humidity of air for humans is 40-60 percent. Dry air is tolerated well under all conditions. High humidity has an unfavorable effect; at high temperatures it facilitates overheating of the body, and at low temperatures it facilitates chilling. The movement of air causes an increase in the body’s heat emission. Therefore, at high temperatures (up to 37° C), wind provides protection of humans from overheating, and at low temperatures it promotes chilling. The combination of wind with low temperatures and high humidity is especially adverse for humans. The significance of ionization of the air is well known. Light ions with negative charges exert a positive effect on the body. A number of devices have been proposed for ionization of air.

G. I. SIDORENKO

Air pollution. The growth of the scale of economic activity increases air pollution. The development of industry, power engineering, and transportation is leading to an increase in the content of carbon dioxide (by 0.2 percent of the amount in the air annually) and a number of other harmful gases in the air. Metallurgical and chemical enterprises and also thermal electric power plants pollute the air with sulfur dioxide, nitrogen oxides, hydrogen sulfide, and halogens and their compounds. Another serious source of air pollution is automobile transportation. According to some calculations, 1,000 automobiles discharge with their exhaust gases 3.2 tons of carbon monoxide, 200-400 kg of other products of incomplete fuel combustions, and 50-150 kg of nitrogen compounds into the air in one day. The pollution of air by solid particles is very great. In Pittsburgh (USA), 610 tons of dust is precipitated annually per square mile (259 hectares). Industrial enterprises, thermal electric power plants, automobile transportation, and forest fires and dust storms occuring as a result of the improper use of land increase the concentration of solid particles (dust and smoke) in the air to such an extent that this substantially (by 20-40 percent) decreases the solar radiation reaching the earth’s surface in the area of large cities. The scale of such processes may be judged by the fact that dust storms from 1930 to 1934 in the USA carried away up to 25 cm of topsoil and transported about 200 million tons of dust for distances of up to 1,000 km.

Air pollution leads to a deterioration of living conditions for humans, animals, and plants. The harmful effect on living organisms under such circumstances is caused not only by the primary components of industrial wastes but also by new toxic substances formed by them—the so-called photoxidants. Air pollution may sometimes attain such a scale that it leads to an increase in morbidity and mortality of the population. Radioactive air pollutants are particularly dangerous; as a result of the constant movement of air masses, they are global in character. Certain air pollutants cause occupational diseases. The influence of air pollutants on living conditions is extremely great. In the USSR laws that provide for the necessity of monitoring air quality and for the responsibility of the heads of industrial enterprises for the thorough cleaning and rendering harmless of industrial gases before their discharge into the atmosphere have been adopted for conservation of nature. As obligatory measures in designing and building cities, villages, and industrial sites, the law provides for the creation of sanitary protection zones (breaks) and the transfer out of residential areas of industrial enterprises that create health hazards.

Analysis of air. The maximum permissible concentrations (usually in mg// or per cu m of air) of harmful and explosive substances in the air environment of a manufacturing plant are regulated by law. Methods of air analysis depend on the aggregate condition of the substance being dealt with. For example, dust and aerosols are usually trapped with cotton wool or paper filters (glass filters are sometimes used for trapping aerosols); fogs and gases are usually absorbed by liquids. The most common methods for determining the content of harmful substances in the air are photometric analysis, nephelometry, and turbidimetry. Automatic gas analyzers are most frequently used for rapid determination of small concentrations of toxic and explosive substances in the air. The determination of radioactive pollutants occupies a special place in air analysis.

Air in technology. Because of the oxygen contained in air, it is used as a chemical agent in various processes, among them the burning of fuel, the smelting of metals from ores (blast-furnace and open-hearth processes), and the commercial manufacture of many chemical compounds (sulfuric and nitric acids, phthalic anhydride, ethylene oxide, acetic acid, acetone, and phenol); the value of air as a chemical agent is substantially increased by increasing its oxygen content.

Air is the most important industrial raw material for obtaining oxygen, nitrogen, and inert gases. The physical properties of air are used in heat and sound insulation materials and in electrical insulation devices; its elastic properties are used in pneumatic tires; and compressed air serves as the operating member for performing mechanical work (pneumatic machines, jet and spraying apparatus, perforators, and so on).

Artificial air. Artificial air, which is more accurately called artificial atmosphere, is a mixture of gases suitable for breathing. It was first used in medicine for diseases accompanied by oxygen deficiency (40-60 percent oxygen mixed with ordinary air, or 95 percent oxygen and 5 percent CO₂). Similar artificial gas mixtures are used in high-altitude aviation and in mine-rescue work. Artificial air is particularly significant in diving. Ordinary air is not suitable for work under pressures substantially higher than normal; under these conditions air has a narcotic effect, and the increase in solubility of nitrogen in the blood and body tissues makes rapid ascent of the diver to the surface dangerous. The discharge of nitrogen bubbles from the blood may cause caisson disease and death. For this reason, nitrogenless gas mixtures containing mainly helium (up to 96.4 percent) and oxygen (2-4 percent) at pressures of 0.7-2 MN/m² (7-20 atm) have been tested in the last 10-15 years for work at great depths (under conditions of high pres-sure). Such mixtures eliminate the danger of caisson disease; however, they produce some discomfort because of the high thermal conductivity of helium; a substantial change in voice timbre is also observed in such an atmosphere.

The problem of artificial air is also being dealt with in the construction of manned spacecraft. The Soviet spacecraft Vostok and Voskhod were equipped with a special system that maintained a close-to-normal air composition: partial pressure of oxygen, 20-40 kN/m²; volume concentration of CO₂, 0.5-1 percent. The American Gemini spacecraft had a pure oxygen atmosphere at a pressure of about 0.3 atm.

REFERENCES

Khrgian, A. Kh. Fizika atmosfery, 2nd ed. Moscow, 1958.
Nekrasov, B. V. Osnovy obshchei khimii, vol. 1. Moscow, 1965.
Battan, L. J.Zagriaznennoe nebo. Moscow, 1967. (Translated from English.)
Armand, D. Nam i vnukam, 2nd ed. Moscow, 1966.
Sokolov, V. A. Gazy zemli. [Moscow, 1966.]
Opredelenie vrednykh veshchestv v vozdukhe proizvodstvennykh pomeshchenii, 2nd ed. Moscow, 1954.
Rukovodstvo po kommunal’noi gigiene, vol. 1. Moscow, 1961.

V. L. VASILEVSKII

What does it mean when you dream about air?

Air was one of the four elements of classical Greek philosophy (the others were earth, fire, and water). As such it is a complex symbol, and interpreting the meaning of air depends heavily on the larger context in the dream. The classical element air symbolizes the intellect, ideas, creativity, communication, travel, and related matters. Thus, the state of the air (e.g., whether clear or foggy) may be a commentary on one’s ideas or communications.

air

[er] (chemistry) A predominantly mechanical mixture of a variety of individual gases forming the earth's enveloping atmosphere. (mechanical engineering) air-injection reactor

air

i. The mixture of gases composing the earth's atmosphere.
ii. The realm or medium in which aircraft operate.

Air

Alarm (See WARNING.)Aeolusgod of the winds. [Gk. Myth.: Zimmerman, 9]Aethergod of whole atmosphere. [Gk. Myth.: Jobes, 42]Auraewinged nymphs of breezes. [Rom. Myth.: LLEI, I: 323]Junoin allegories of elements, personification of air. [Art: Hall, 128]sylphspirit inhabiting atmosphere in Rosicrucian philosophy. [Medieval Hist.: Brewer Dictionary, 1055]

air

1. the mixture of gases that forms the earth's atmosphere. At sea level dry air has a density of 1.226 kilograms per cubic metre and consists of 78.08 per cent nitrogen, 20.95 per cent oxygen, 0.93 per cent argon, 0.03 per cent carbon dioxide, with smaller quantities of ozone and inert gases; water vapour varies between 0 and 4 per cent and in industrial areas sulphur gases may be present as pollutants 2. Musica. a simple tune for either vocal or instrumental performance b. another word for aria3. Austral informal the height gained when getting airborne in surfing, snowboarding, etc 4. Astrology of or relating to a group of three signs of the zodiac, Gemini, Libra, and Aquarius

AIR

(standard)A future infrared standard from IrDA. AIR willprovide in-room multipoint to multipoint connectivity. AIRsupports a data rate of 4 Mbps at a distance of 4 metres, and250 Kbps at up to 8 metres. It is designed for cordlessconnections to multiple peripherals and meeting roomcollaboration applications.

See also IrDA Data and IrDA Control

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What does it mean when you dream about air?

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Patient discussion about air

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Synonyms for air

noun wind

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noun atmosphere

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noun tune

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noun manner

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noun affectation

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verb broadcast

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verb publicize

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verb ventilate

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phrase up in the air

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phrase walking on air

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Synonyms for air

noun the gaseous mixture enveloping the earth

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noun the celestial regions as seen from the earth

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noun a natural movement or current of air

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noun a general impression produced by a predominant quality or characteristic

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noun behavior through which one reveals one's personality

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noun artificial behavior adopted to impress others

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noun a pleasing succession of musical tones forming a usually brief aesthetic unit

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