Final answer:
A boundary between two air masses is known as a front, which is a term used in meteorology to predict weather patterns, alongside important features like high and low pressure regions and isobars on a weather map.
Step-by-step explanation:
A boundary between two air masses is called a front. Meteorologists use weather maps to describe and predict weather, which include several important features. For instance, regions of high (H) and low (L) pressure significantly influence weather conditions, and the gray lines on a weather map represent locations of constant pressure known as isobars. Atmospheric wind and weather phenomena occur primarily in the troposphere, which extends to about 12 km above the Earth's surface.