In which of the following conditions should windshield wipers be used?

Windshield wipers are an essential tool for maintaining clear visibility while driving, and their use is not limited to just one type of weather condition. Utilizing them during any conditions that impair visibility is the most prudent approach. This includes rain, but also encompasses situations such as light mist, snow, sleet, or any weather phenomenon that creates obscured views through the windshield.

For instance, in foggy conditions, while the fog itself may not cause moisture on the glass, visibility can be severely diminished, and using wipers may help clear any accumulated condensation. Similarly, during snow, particularly when it's light or when it's mixed with rain, wipers can help maintain a clear line of sight.

When visibility is compromised, whether from precipitation or other environmental factors, the key factor is the driver’s ability to see clearly. Therefore, it's critical to use windshield wipers anytime visibility is impaired, rather than limiting their use to specific scenarios like rain or heavy snow. This comprehensive understanding ensures safety on the road regardless of the prevailing weather conditions.