When two air masses meet at a front, they typically do not mix. Instead, the denser air mass (usually the colder one) forces the less dense air mass (usually the warmer one) to rise. This creates a zone of transition called a front, which is characterized by distinct differences in temperature, humidity, and wind direction.

Here's a breakdown:

* Cold Front: A cold air mass pushes into a warmer air mass, causing the warm air to rise rapidly. This results in thunderstorms, heavy rain, and sometimes tornadoes.

* Warm Front: A warm air mass pushes into a cooler air mass, gradually lifting the cold air. This causes light to moderate rain, fog, and a gradual increase in temperature.

* Stationary Front: Two air masses meet but neither is strong enough to displace the other. This can lead to prolonged periods of rain or snow.

* Occluded Front: A cold front overtakes a warm front, trapping warm air aloft. This can cause a variety of weather conditions, including heavy precipitation and strong winds.

It's important to remember that air masses don't just blend seamlessly together. They maintain their individual characteristics and interact with each other in specific ways, leading to the diverse weather patterns we experience.