What can cause black ice on roads?

Black ice, also known as black ice sheets or invisible ice, forms when moisture on the road freezes. This typically occurs under specific conditions, particularly when rain falls on cold pavement. In situations where the air temperature is cold enough, this rain can freeze almost instantly upon contact with the cold surface, creating a transparent layer of ice that can be very difficult to see, hence the name "black ice."

The other scenarios presented do not lead to the formation of black ice. On a sunny day, the heat from the sun would typically help to melt any ice or snow present on the roads, reducing the risk of black ice. Thunderstorms generally create heavy rain and, depending on temperature, can lead to wet conditions but not specifically to black ice, which forms in cooler conditions. Windy conditions might contribute to road drying or snow drifting but do not directly cause the formation of black ice as rain does.