Here's why:

* Cloud Classification: Clouds are categorized based on their altitude, which is the height of their base above the ground.

* High-Level Clouds: High-level clouds are the highest group, typically found between 5,000 and 13,000 meters (16,400-42,600 feet). They are composed primarily of ice crystals.

* Specific High-Level Clouds: The specific types of high-level clouds include cirrus (Ci), cirrocumulus (Cc), and cirrostratus (Cs).

Let me know if you'd like to know more about any specific type of high-level cloud!