Across a front, one discontinuity is easily recognized. Which change is it?

• A. Change in humidity
• B. Change in temperature
• C. Change in cloud type
• D. Change in wind speed

Answer: (B)

Across a front, the air masses on each side have different temperatures, so the boundary produces a noticeable change in temperature. That sharp temperature difference is the clue pilots rely on to identify the front, since you can feel or measure a sudden warm or cold snap as you cross it. Changes in humidity or cloud type can occur, but they’re less immediately obvious and can vary with altitude and moisture conditions, while wind speed changes are not as consistently tied to the frontal boundary. So the change you’re most likely to notice across a front is in temperature.