In which of the following conditions is supercooled rain likely to occur?

Supercooled rain occurs when liquid water droplets exist in a liquid state at temperatures below freezing. This phenomenon is most likely to take place in conditions where humidity is present, combined with subzero temperatures.

When moist air encounters cold air, it can lead to the formation of supercooled droplets. These droplets remain in liquid form despite being below the freezing point, primarily because they do not encounter a surface to freeze upon or when the atmospheric pressure is sufficiently low. In this context, high humidity is crucial as it provides the necessary moisture content for the formation of liquid droplets, while subzero temperatures ensure that the droplets do not freeze into ice immediately.

The other conditions listed do not support the formation of supercooled rain as effectively. For example, clear and dry air lacks sufficient moisture, high turbulence typically promotes droplet formation into ice or precipitation patterns that do not allow supercooled rain to exist, and warm front passages usually bring warmer air that does not support the freezing conditions required for supercooled droplets. Thus, the combination of humidity and subzero temperatures is the most conducive to the occurrence of supercooled rain.