One weather phenomenon which will always occur when flying across a front is a:

• A. Change in wind direction
• B. Change in temperature
• C. Change in humidity
• D. Cloud formation

Answer: (A)

Crossing a front means moving from one air mass to another, each with its own wind pattern. Because the air mass on the other side of the boundary has a different flow, the surface wind tends to shift direction when you pass through the front. This change in wind direction is the most reliable indicator you’ll notice as you cross a frontal boundary, which is why it’s the best answer. Temperature and humidity often change as you move into a new air mass and clouds frequently form, but those changes aren’t guaranteed in every frontal passage, whereas a wind-direction shift generally accompanies the crossing.