FAA Ground School Practice Test

A stable air mass is most likely to have which characteristic?

1. Good surface visibility

2. Strong winds

3. Sufficient turbulence

4. Poor surface visibility

The correct answer is: Poor surface visibility

A stable air mass is characterized by a well-defined structure, where cooler air lies above warmer air at the surface. This setup inhibits vertical movement, leading to conditions that are typically smooth and layered. Good surface visibility is usually associated with stable conditions, as there are fewer disturbances in the air to stir up particles and create haze or obscurations. Strong winds are often a feature of unstable air masses that can produce turbulent conditions. Similarly, sufficient turbulence is indicative of instability where vertical air currents can thrive, promoting variations in weather patterns. When instability is low, the lack of vertical mixing tends to trap moisture and pollutants near the surface, which can result in poor visibility. Thus, the presence of stable air is closely linked to reduced visibility due to the tranquility it fosters at lower altitudes.