Which term describes an extensive body of air with uniform temperature and moisture in a horizontal plane?

• A. Front
• B. Air Mass
• C. Jet Stream
• D. Inversion

Answer: (B)

An air mass is an extensive body of air that has relatively uniform temperature and moisture content over large horizontal areas. This uniformity comes from forming over a source region with consistent conditions, so the air mass carries those same characteristics as it moves. That makes it the best fit for the description of a large, horizontally uniform body of air.

A front, by contrast, is a boundary between two different air masses, where properties change rather than remain uniform. A jet stream is a fast-moving band of air high in the atmosphere, not defined by uniform temperature and moisture across a broad area. An inversion refers to a layer where temperature increases with height, which describes a vertical structure rather than a horizontally uniform body of air.