Which type of clouds typically indicate a transition in weather patterns at mid-altitudes?

Altostratus clouds are indeed indicative of a transition in weather patterns, particularly at mid-altitudes, typically ranging from 6,500 to 20,000 feet. These clouds often form ahead of a weather front and can signal the approach of rain or storms. Their presence usually indicates moisture in the atmosphere, and they tend to cover the sky with a gray or blue color, diffusing sunlight and creating a uniform appearance.

When altostratus clouds are observed, it may suggest that a change in weather is imminent—often heralding precipitation, usually in the form of rain or snow, as the front associated with the clouds gets closer. This characteristic makes them key indicators for predicting weather changes.

Cumulonimbus clouds are typically associated with thunderstorms and severe weather rather than mid-altitude transitions. Cirrus clouds, while also high-altitude clouds that can indicate future weather changes, are not associated with the same mid-altitude weather transitions. Cumulus clouds usually represent fair weather and do not indicate an imminent change in weather patterns. Thus, the characteristics and typical formations of altostratus clouds support their role as indicators of weather transitions at mid-altitudes.