A weather front is a boundary separating two masses of air of different densities, and is the principal of them meeting but not mixing. In surface weather analyses, fronts are depicted using various colored triangles and half-circles, depending on the type of front.
A cold front is when the boundary of an advancing mass of cold air (high-pressure system) and the warm air (low-pressure system) meet but don't crossover and the cold air pushes and forces the warm air up. A cold front is defined as the transition zone. Cold fronts generally move from northwest to southeast.
A warm front is a boundary of a cold mass and a warm mass and the warm mass replaces the cold air mass. A warm front is also defined as the transition zone. Warm fronts generally move from southwest to northeast.
