Which type of clouds would typically signal fair weather?

Cumulus clouds are typically associated with fair weather due to their characteristic appearance and formation process. These clouds are often fluffy, white, and have a flat base, resembling cotton balls. They form when warm air rises, cools, and condenses, leading to a more stable atmosphere. As they develop, cumulus clouds indicate that there is sufficient moisture in the air, but they usually do not bring precipitation.

In contrast, stratus clouds tend to cover the sky in a uniform layer and can produce overcast conditions and light rain. Cirrus clouds, while usually high in the atmosphere and indicating good weather, often signal that a change in weather might be on its way, such as an approaching storm due to their association with warmer fronts. Nimbus clouds, particularly cumulonimbus, are thunderstorm clouds that often bring heavy rain, wind, and severe weather.

Therefore, cumulus clouds are the best representation of fair weather conditions among the options listed.