The phrase "a layer of air" is correct and usable in written English.
It can be used in contexts discussing atmospheric science, environmental studies, or any situation where the concept of air being layered is relevant.
Example: "The temperature decreases with altitude due to the presence of a layer of air that traps heat near the Earth's surface."
Alternatives: "a stratum of air" or "a sheet of air".
When it's hot, there is nothing like wearing a layer of air.
This is because the resistance is so great that a layer of air makes no appreciable difference.
The study backs UN research that suggests a layer of air pollution, the "brown cloud", regularly covers the upper atmosphere over Asia between January and March and could precipitate an environmental disaster that could affect billions of people.
The basic idea is to build a partially evacuated tube, inside which capsules would float on a layer of air, pulling themselves along with a fan and getting extra propulsion from electromagnets in the tube's walls.
Atmospheric brown cloud, a layer of air pollution containing aerosols such as soot or dust that absorb as well as scatter incoming solar radiation, leading to regional and global climatic effects and posing risks to human health and food security.
When air is pumped rapidly out of small holes in a ship's hull, the swarming bubbles will quickly join together and coat the hull with a layer of air a centimetre or two thick.
In insects, the chorion has a layer of air-pores in the otherwise solid material which provides very limited capability for respiratory function.
Wind machines that stir up the air, for example, provide heat when temperature inversions trap cold air under a layer of warm air.
When the hot air hits a layer of cold air it dissipates, and the bird flies off on a thermal, heading toward its nesting grounds some 45 miles to the south.
A Clean Air Sandwich Smog can be at its worst in a thermal inversion, when the temperature of the atmosphere increases with altitude, creating a layer of stable air that traps the dirty air underneath.
Air normally cools with altitude, but during an inversion warm air settles above a layer of cool air near the surface.
