What type of clouds are classified as high level?

High-level clouds are classified based on their altitude, generally occurring above 20,000 feet (approximately 6,000 meters). These clouds primarily consist of ice crystals due to the cold temperatures at such heights. Cirrus clouds are characteristic of this category and are thin, wispy clouds that often appear white and feathery.

They play a significant role in atmospheric processes, including the regulation of heat and moisture in the atmosphere. When observing cirrus clouds, pilots can infer information about weather patterns, such as an approaching front or changes in atmospheric conditions, since they often precede storm systems. Their presence can indicate high-altitude turbulence as well, which is crucial for flight operations.

The other options involve different types of clouds: cumulus clouds are typically associated with warmer weather and convection, stratus clouds generally form at low altitudes and create overcast skies, and "circuit" is not a recognized cloud type in meteorology. Understanding these classifications helps in interpreting weather patterns and making informed decisions in aviation and meteorology.