Figure 26 – Fronts: (a) Warm front; (b) Cold front

6.2. Cold Front

When a cold and dense airmass forces its way under warm and lighter airmass it makes the warm and lighter airmass to ride over it. This type of front is called cold front. The effect of friction retards the air motion near the ground, while the free air aloft has a higher velocity. This causes the cold front to become much steeper than the warm front.