Warm air advances only when cold air retreats, so a warm front moves toward which air mass?

• A. Cooler
• B. Warmer
• C. Dry
• D. Stable

Answer: (A)

A warm front moves into cooler air because it forms where a warm air mass slides over and overtakes a retreating cooler air mass. The boundary advances into the cooler air, lifting it gradually as the warm air glides over it. So the air mass that the front moves toward is cooler. The other options don’t fit the movement: a front isn’t defined by moving into warmer air, and “dry” or “stable” describe moisture or atmospheric stability, not the direction of a warm front’s advance.