<span>Zygomatic major is the primary muscle that elevates the corners of your mouth.</span>
Fast-moving cold fronts force the warm air ahead of them to rise more quickly than slow movers. The clouds and rain are mostly along the front or ahead of it, and heavy rain or thunderstorms are common. A slow-moving front lifts the warm air more gradually; the rain is less intense, and the clouds form along and *behind* the surface cold front.
