Understanding Weather Reports: Warm Fronts
If warm air moves in such a way that it advances onto and replaces the cooler air in its path, the leading edge of the warm air mass found at the earth’s surface (the ground) is known as a warm front. When a warm front passes through, the weather becomes noticeably warmer and more humid than it was before. The weather map symbol for a warm front is a red curved line with red semi-circles. The semi-circles point in the direction the warm air is moving.