Answer:
air masses
Step-by-step explanation:
You may have heard of the cold front and the hot front in some news that provides weather information. These fronts are called air fronts in meteorology. They are formed when two different air masses meet directly, which end up establishing contact between them. These air masses are cold and hot and the region in the middle of the two is the front that will be cold or hot, depending on which air mass is predominant at the moment.