During a frontal passage, which parameter is not listed as changing?

• A. Humidity
• B. Temperature
• C. Wind speed
• D. Dew point

Answer: (A)

When a front passes, one air mass replaces another, so you see clear changes in several atmospheric properties as the air mass characteristics shift. Temperature changes abruptly as the cooler or warmer air replaces what’s in place, and the wind often shifts direction and speed due to the evolving pressure field and the new air mass sweeping in. The moisture content of the air also changes because the incoming air mass carries a different amount of water vapor, which shows up as a change in dew point.

Humidity, in this framing, is not singled out as changing because it’s a derived measure that depends on both temperature and moisture. The dew point directly reflects the air’s moisture content, and temperature is the primary driver of how much the relative humidity can change. In other words, dew point captures the moisture change across the front, while humidity (as relative humidity) can be more variable and less diagnostic on its own in this context. So the parameter not listed as changing is humidity.