What is the boundary between different air masses called?

• A. Weather front
• B. Climate
• C. Jet stream
• D. Trade wind

Answer: (A)

When two large bodies of air with different temperatures and humidity meet, their boundary is called a weather front. This boundary marks where the air masses interact, and that interaction often causes changes in weather—lifting of air, cloud formation, and precipitation as one mass forces the other to rise and condense. Fronts come in several types: a cold front occurs when cold air advances and pushes under warmer air, often bringing thunderstorms or heavy rain; a warm front forms when warmer air overrides cooler air, leading to more gradual, widespread precipitation; a stationary front sits still and can cause prolonged rain; and an occluded front develops in a cyclone when a cold front catches up to a warm front.

The other options describe different things: climate is the long-term pattern of weather in a region; the jet stream is a fast-moving, high-altitude river of air; trade winds are steady winds near the equator.