Which statement best describes a temperature inversion?

• A. A stable layer of air
• B. Deep convection
• C. Turbulent boundary layer
• D. Strong wind shear

Answer: (A)

A temperature inversion is when air temperature increases with height, creating a stable layer that resists vertical motion. Because the rising air would enter warmer air above, it becomes cooler than its surroundings and tends to stop rising or sink back, effectively acting like a lid on convection. That stability is why it’s described as a stable layer of air. Inversions can form overnight as the ground radiates heat away or when warm air moves over a cooler layer, and for glider pilots this means thermals are suppressed and lift is limited above the inversion while the air below can be unusually smooth. The other descriptions point to different atmospheric conditions: deep convection involves strong rising air due to instability, a turbulent boundary layer refers to the lower, wind-sheared part of the atmosphere, and strong wind shear is about rapid changes in wind with height, not the defining feature of an inversion.