Altocumulus (mackerel sky) clouds with dark stratus cloud beneath near sunset

- Image ID: CXJ2GW
Altocumulus (mackerel sky) clouds with dark stratus cloud beneath near sunset
Denise Dethlefsen / Alamy Stock Photo
Image ID: CXJ2GW
Altocumulus clouds form between 6500 feet (2000 meters) and 20,000 feet (6000 meters). When mid-altitude altocumulus or high-altitude cirrocumulus display an undulating or rippled appearance, the so-called 'mackerel sky,' they often signal a change in weather.
Location: northern California, USA