Objects and people that hover in the air will always, ''always'' bob up and down, as if floating on some invisible surface of water. This is typically because being perfectly motionless gives the unpleasant impression of being "stuck" in the air. The floating is often accompanied with a ''whoosh'' sound, for no other reason than the RuleOfCool.

The most JustForFun/{{egregious}} instances of this trope are when objects in ''zero gravity'' bob up and down, despite the fact that 'down' doesn't exist here. This conclusively proves that SpaceIsAnOcean.

SelectiveGravity causes many items in video games to do that.

{{Justifi|edTrope}}cation usually invokes one of the following:
* It is possible that the bobbing is merely the character performing drift correction. Satellites in orbit, for a RealLife example, have thrusters to keep them from drifting out of the required orbit all the time.
* In RealLife, of course, few things float in midair, and those that do (such as tethered or semi-deflated helium balloons) tend to bob in all but the stillest air -- or to be surrounded (as a hummingbird or helicopter) by a blur of corrective motion. And, of course, things floating on water bob up and down too. So this trope seems to derive from carrying learned expectations about the natural behaviour of objects over into extrapolations about ''un''natural behaviour.
* In animated cartoons, especially lower budget ones, midair bobbing [[RuleOfPerception serves the pragmatic purpose]] of establishing that a character or object is ''supposed'' to be in the air, and isn't just misaligned with the background.
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!!Examples:
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[[folder: Anime ]]

* Urd in ''Manga/AhMyGoddess'' likes to do this when "sitting" rather than sitting on furniture. She takes after Hild, who probably expends less energy at it than you would on breathing, being the equal and opposite number of that verse's {{God}}.

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[[folder: Film ]]

* Luke Skywalker and the other X-Wing pilots do a good bit of this in ''StarWars''. You can see it, for example, in this [[http://www.youtube.com/watch?v=vmRfj2dF7gM Youtube clip]]. It's only when they do a close-up cockpit shot of one of the X-Wing pilots. Everybody just kind of...bobs. Very odd, especially since the X-Wings themselves certainly aren't bobbing around in the longer shots. The speeders largely subvert this however in that when they are idling they are completely motionless and often don't even react when someone is mounting/dismounting/operating them (aside from Luke's speeder in ANH, but that is mentioned on screen to be a bit of a cheapo/junker.)
* In ''Film/{{Apollo 13}}'', the bobbing was due to the zero-gravity set (which was in the Vomit Comet, an airplane being flown in a ballistic trajectory) being buffeted by the atmosphere; when other scenes were later filmed in normal gravity back on the ground, the actors bobbed to match the zero-gravity footage.

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[[folder: Literature ]]

* Peeves in ''Literature/HarryPotter'' bobs most likely not due to the qualities of floating, but due to the fact that he has the energy and attention span of a ritalin deprived ADHD 6 year old on a sugar rush.
** Many other things float without this quality. Snape (when being levitated by Sirius) does bob, but that's more due to Sirius's lack of fine control.

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[[folder: Video Games ]]

* Anyone affected by the "Float" spell in any given ''Franchise/FinalFantasy'' game will hover above the ground for a while. Flying enemies also did this in ''IV'' through ''VI''.
* Lt. Magnezone and several other fliers and levitators in the ''VideoGame/PokemonMysteryDungeon'' games.
* The player in ''VideoGame/{{Descent}}''. Since you're in a spaceship, it's presumably drift correction.
* The Allied Rocketeers in ''VideoGame/CommandAndConquerRedAlert 2'' do this.
* Happens in ''VideoGame/CityOfHeroes'' when the hover power is engaged and the hero isn't otherwise moving. The [[http://www.cityofheroes.com/ official website]] header makes it even more obvious.
* Giving an enemy in an ''RPG Maker'' game the 'flying' attribute will cause it to midair bob in battle.
* In ''Franchise/{{Halo}}'', the thrones of the Prophets and Rtas 'Vadum (aka [[FanNickname Half-Jaw]]) both behave this way.
* Watch the ships in ''[[VideoGame/{{Wipeout}} Wipeout HD]]'' when at a standstill. As one would reasonably expect from machines designed to perform best at very high speeds, the ships appear to be performing drift correction to avoid shifting sideways as well as bobbing naturally with air currents, especially close to the ground, and when they move faster, they stop doing this--presumably due to their shapes enacting aerodynamic stability on the ships, allowing them to fly without wiggling everywhere.
* The fire pets from the "Firemaker's Curse" quest in ''VideoGame/RuneScape'' do this.
* All "Flying" characters in ''VideoGame/MarvelAvengersAlliance'' do this for their idle animation.
* Several characters in ''VideoGame/CaveStory'' bob while flying, such as bats (which serve the purpose as obstacles, especially at the beginning when player has no weapons) and Misery (who bobs for no other reason than because ''not'' bobbing looks weird).
* In the ''VideoGame/{{Glider}}'' series, the player's glider will bob up and down at the top of updrafts, as an entirely natural consequence of the VentPhysics.

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[[folder: Web Original ]]

* In one [[WebAnimation/HomestarRunner Strong Bad]] email, Bubs is shown to have once possessed the power of flight. Bubs bobs.
* A pantomimed version of this is used in HolyMusicalBatman to indicate when Superman is flying. Well, in addition to being lifted from behind by a taller cast member and making whooshing noises like a five-year-old. In a stage musical about superheroes, CoconutSuperpowers like this are to be expected and actually add a lot to the charm.

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[[folder: Western Animation ]]

* ''WesternAnimation/ThePowerpuffGirls'' are the queens of this trope: not only do they perform Midair Bobbing, they do it ''in unison''.
* Fairy Godparents in ''WesternAnimation/TheFairlyOddparents'' all bob like this. And they all do insync, as if floating on the same invisible plain.
** And so do some of their ''buildings''.
* As do both Starfire and Raven from ''WesternAnimation/TeenTitans''. But mostly Starfire.
* The hoverbikes in ''WesternAnimation/TheVentureBrothers''.
* Happens in the episode of ''WesternAnimation/ChipNDaleRescueRangers'' where they launch into space on a spaceship. This one is particularly silly; while whatever AppliedPhlebotinum is used in the other examples may produce MidairBobbing, physical weightlessness definitely doesn't.
* All over the place in TheDCAU. Occasionally averted, which tends to look weird.
* Happens in ''WesternAnimation/AvengersEarthsMightiestHeroes'' when IronMan flies into space to search for BigBad Kang's ship. Of course, this was right after coming to a stop [[SpaceFriction without benefit]] of retro-rockets.
* The pilots of ''WesternAnimation/DastardlyAndMuttleyInTheirFlyingMachines'' bob in the air, whether they are flying or their planes are stationary.
* Billy does this in ''WesternAnimation/DudeThatsMyGhost'', due to being, well, a ghost.

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[[folder: Real Life ]]

* There is a similar phenomenon in aerospace called a "pogo oscillation", a reference to the bouncing motion of a pogo stick. It results when a problem with the fuel system causes fluctuations in the fuel flow rate, causing likewise fluctuations in engine thrust output, causing likewise fluctuations in acceleration. This fluctuation in acceleration worsens the fluctuations in the fuel flow rate, forming a vicious circle that eventually leads to a structural failure in the vehicle and, in some cases, complete and total vehicle disintegration.
* Many aircraft, especially when flying in formation, will do this to a degree. It is usually caused by the pilot (or the in-flight computer) making constant adjustments to the aircraft's control surfaces to stay on course or in formation.
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