Refer to figures.
The warm front slopes forward. The lighter, warmer, moist air is forced up and over the heavier, colder air, rising very gently along a slope of about 1:150. This gentle slope results in minimal vertical flow, leading to stratiform clouds and light to moderate continuous drizzle, rain, or snow along the warm front.

In contrast, the cold front slopes backward because the heavy, cold air forces itself underneath the warmer, lighter air. With a slope of between 1:50 and 1:80, the cold front is steeper than the warm front but still relatively gentle, causing stratiform clouds due to the gentle uplift. However, the cold front also has a bulging "cold nose" near the surface, creating an unstable area where warm, buoyant air lies beneath cold air. This instability triggers rapid vertical uplift, resulting in large cumuliform clouds.