Which front is usually preceded by clouds of decreasing altitude?

• A. Cold Front
• B. Warm Front
• C. Occluded Front
• D. Stationary Front

Answer: (B)

The situation described is tied to how warm air interacts with cooler air ahead of a front. When a warm front approaches, warm, moist air glides over the cooler air, producing wide bands of stratiform clouds that form at successively lower levels as the front nears. You often first see high clouds (cirrus), then mid-level clouds, and finally lower clouds (stratus) as the warm front approaches, so the cloud bases appear to descend in altitude. This gradual lowering of cloud base results in the characteristic widespread, gentle precipitation ahead of a warm front.

In contrast, a cold front lifts the air more abruptly and vigorously, leading to tall, vertically developed clouds like cumulonimbus that can climb to great heights; these do not show a pattern of decreasing cloud altitude before the front. Occluded and stationary fronts have their own distinct cloud patterns that don’t center on a consistent decrease in cloud base prior to the front.