How Things Fly ~ National Air and Space Museum 

Visit Page for Flying Instructionals: https://howthingsfly.si.edu/ask-an-explainer/air-fluid

Is Air Fluid? 

Q:
Is air a fluid?
A:

Yes! A fluids is any substance that flows. Air is made of stuff, air particles, that are loosely held together in a  gas form. Although liquids are the most commonly recognized fluids, gasses are also fluids.  Since air is a gas, it flows and takes the form of its container.