In basketball, an air ball is a shot that misses both the rim and the backboard.

The usage may have an ironic subtext to it; "air" is generally used positively in basketball, often relating to jumping ability. The "air ball", on the other hand, is widely perceived as the opposite: a signifier of an unskilled player. To perform an air ball is often to be ribbed by one's co-players.

Although the term has often been deemed to have been created by the Cameron Crazies of Duke University, such attribution is highly suspect. Some have pointed to the date of February 24, 1979, during a college basketball game between the Duke University Blue Devils and the North Carolina Tar Heels, as the first recorded use of "air ball". During a highly unusual Duke-UNC game, in which UNC failed to score during the first half, the Duke crowd broke into a chant of "air ball" after Tar Heel player Rich Yonakor took UNC's only shot of the half, which missed the rim. It has become one of the most iconic jeers in college basketball.

The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).

Atmospheric stratification describes the structure of the atmosphere, dividing it into distinct layers, each with specific characteristics such as temperature or composition. The atmosphere has a mass of about 5×10¹⁸ kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. An altitude of 120 km (75 mi) is where atmospheric effects become noticeable during atmospheric reentry of spacecraft. The Kármán line, at 100 km (62 mi), also is often regarded as the boundary between atmosphere and outer space.

A ball is a round, usually spherical but sometimes ovoid, object with various uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch, marbles and juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black powder weapons use stone and metal balls as projectiles.

Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see bouncing rubber balls (albeit solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials.

As balls are one of the most familiar spherical objects to humans, the word "ball" is used to refer to, or to describe, anything spherical or near-spherical.