A cold front is formed when a cold air mass replaces a warm air mass. Which term describes this boundary?

A cold front is formed when a cold air mass replaces a warm air mass. Which term describes this boundary?

• A. Unstable atmosphere
• B. Cold front
• C. Thermal layer
• D. Warm front

Answer: (B)

When a cold air mass moves in and replaces a warmer air mass, the boundary between them is a cold front. Fronts are the defined edges where air masses with distinct temperatures and humidities meet. The cold air, being denser, wedges underneath the warm air and lifts it, often leading to quick cloud development, showers or storms, and a noticeable drop in temperature as you pass the front. The other terms don’t describe this boundary: an unstable atmosphere is a thermodynamic state that favors convection, not a boundary between air masses; a thermal layer isn’t a standard term for a front; a warm front is the boundary where warm air overrides cooler air, the opposite scenario.

When a cold air mass moves in and replaces a warmer air mass, the boundary between them is a cold front. Fronts are the defined edges where air masses with distinct temperatures and humidities meet. The cold air, being denser, wedges underneath the warm air and lifts it, often leading to quick cloud development, showers or storms, and a noticeable drop in temperature as you pass the front. The other terms don’t describe this boundary: an unstable atmosphere is a thermodynamic state that favors convection, not a boundary between air masses; a thermal layer isn’t a standard term for a front; a warm front is the boundary where warm air overrides cooler air, the opposite scenario.