The term 'HIGH MOUNTAIN AIR' can be broken down into two crossword solutions: ALP, which is a three letter word, and HIGH MOUNTAIN. ALP is an abbreviation for the Alps, a MOUNTAIN range in Europe that stretches from Austria and Slovenia in the east, through Italy, Switzerland, Liechtenstein, and Germany to France in the west. The Alps are one of the most iconic MOUNTAIN ranges in the world, and are known for their HIGH peaks and stunning views. HIGH MOUNTAIN air refers to the crisp, clean air found at HIGH altitudes in the mountains. This air is often considered to be some of the purest and freshest air on Earth.