What is a common indicator of a cold front passage?

A common indicator of a cold front passage is a sudden temperature drop and wind shift. When a cold front moves through, it displaces warm air ahead of it, causing the temperature to drop sharply as the colder air mass takes over. This transition can often be accompanied by a distinctive shift in wind direction, as the winds often change from southerly or southwesterly (associated with warmer air) to a more northerly direction as the cold front moves in. These characteristics are essential for pilots to understand, as they can greatly affect flying conditions.

The other options describe weather phenomena commonly associated with different atmospheric situations. For example, the presence of warm, humid air moving in generally pertains to the approach of a warm front, leading to gradual weather changes instead of a sudden drop. A gradual increase in humidity can occur ahead of any front but doesn’t signify a cold front specifically, as this can happen with both warm and stationary fronts. Lastly, steady rain over a long period is typically linked to warm fronts, where warm air rises slowly over a retreating cooler air mass, often resulting in prolonged, gentle precipitation rather than the sudden rain showers that can accompany the passage of a cold front. Understanding these nuances is vital for interpreting weather patterns in