The boundary between two different air masses is called:

• A. Front
• B. Boundary layer
• C. Jet stream
• D. Wake turbulence

Answer: (D)

Two large air masses with different temperatures and moisture levels meet, and the boundary between them is called a front. This boundary forms because the contrasting air masses don’t mix easily, so the interface where their properties meet becomes a distinct region. Fronts are associated with changes in temperature and humidity, shifts in wind, and often clouds and precipitation as the less dense air is lifted or overridden by the other mass. Fronts come in types like cold fronts, warm fronts, stationary fronts, and occluded fronts, each with characteristic weather patterns.

The other terms don’t describe this boundary: the boundary layer is the lowest part of the atmosphere influenced by the surface; the jet stream is a high-altitude, fast-flowing air current; wake turbulence is turbulence caused by an aircraft.