What typically signals the onset of a cold front passage?

The onset of a cold front passage is typically signaled by decreasing temperatures and increased humidity. When a cold front approaches, it displaces warmer air aloft, causing an abrupt change in weather conditions. As the cold air moves in, it forces the warmer, moist air to rise. This uplift leads to cooling of the air, resulting in decreased temperatures.

In addition, as the warm air is lifted, the moisture within it can condense to form clouds and precipitation, contributing to a noticeable increase in humidity. The combined effect of this cooling and rising humidity is characteristic of the weather changes accompanying a cold front.

The other choices reflect different weather phenomena. Scattered clouds and rising temperatures typically indicate stable conditions, which do not coincide with a cold front. Light showers and steady temperatures suggest a more stable weather environment rather than the dynamic changes seen with a front. Clear skies and decreasing winds could indicate a high-pressure area, which is not typical of the turbulent conditions presented by an incoming cold front.