Which of the cloud types listed below is NOT a type of low cloud?

Cirrus clouds are classified as high-altitude clouds, typically found at heights above 20,000 feet. They are characterized by their thin and wispy appearance, which differentiates them from low clouds. Low clouds include types like stratus, nimbostratus, and cumulonimbus, all of which form at lower altitudes and have distinct characteristics related to weather patterns. Stratus clouds are often uniform and gray, covering the sky like a blanket, while nimbostratus clouds are thicker and associated with continuous precipitation. Cumulonimbus clouds, although they can be quite tall, begin in the low altitudes and are known for thunderstorms. Hence, the correct answer is cirrus, as it does not belong to the low cloud classification.