What is the boundary between two air masses of different density, often caused by differences in temperature and humidity?

What is the boundary between two air masses of different density, often caused by differences in temperature and humidity?

• A. Frontal storm
• B. Hurricane
• C. Equator
• D. Front

Answer: (D)

A front is the boundary between two air masses that differ in density due to temperature and humidity differences. When warm, moist air meets cooler, drier air, the two masses don’t mix easily, so a distinct edge forms—the front. At this boundary, the lighter air tends to rise over the heavier air, triggering lifting, cooling, and condensation, which leads to cloud formation and often precipitation. That connection between a sharp boundary and the weather you observe is why this term is used. The other options aren’t about boundaries between air masses: a hurricane is a specific tropical storm; the equator is a geographic line; and the term “frontal storm” isn’t a standard meteorological boundary.

A front is the boundary between two air masses that differ in density due to temperature and humidity differences. When warm, moist air meets cooler, drier air, the two masses don’t mix easily, so a distinct edge forms—the front. At this boundary, the lighter air tends to rise over the heavier air, triggering lifting, cooling, and condensation, which leads to cloud formation and often precipitation. That connection between a sharp boundary and the weather you observe is why this term is used. The other options aren’t about boundaries between air masses: a hurricane is a specific tropical storm; the equator is a geographic line; and the term “frontal storm” isn’t a standard meteorological boundary.