A surface-based temperature inversion, which traps fog, haze, or smoke close to the ground and reduces visibility, most commonly forms under which conditions?

Why: The Remote Pilot Study Guide explains that "surface-based temperature inversions occur on clear, cool nights when the air close to the ground is cooled by the lowering temperature of the ground," becoming cooler than the air above it. If humidity is high, the trapped layer can produce clouds, fog, haze, or smoke, diminishing visibility.

• Reverses the actual mechanism — inversions form from nighttime surface cooling, not daytime surface heating, which instead promotes instability, not a stable trapped layer.
• Confuses a surface-based inversion with a frontal inversion; the guide describes frontal inversions as a separate case (warm air spreading over cooler air at a front), not the only way inversions form.