Plain English Meaning

Layers of air sitting on top of one another, each behaving a little differently from the one above or below it.

Full Definition

Distinct horizontal layers of the atmosphere, each with relatively uniform properties such as temperature, moisture, or air density, stacked at different altitudes.

Context Anchor

Seen in discussions of airways, airspace structure, and how aircraft are organized at different altitudes.

Derivation

From the Latin 'stratum,' meaning 'something spread out' or 'a layer.' The same root gives us 'stratus' clouds (flat, layered clouds). It helps to picture the atmosphere as a stack of spread-out sheets rather than one uniform mass.