In terms of cloud height, what is the highest type of cloud order?

Cirrus clouds are classified as high-altitude clouds, typically found at heights above 20,000 feet (6,000 meters). They are composed of ice crystals and are characterized by their wispy, feather-like appearance. These clouds indicate the presence of moisture and are often associated with fair weather, though they can also signal an approaching warm front.

In contrast, the other types of clouds listed are formed at lower altitudes. Stratus clouds form at low levels and appear as uniform gray sheets, often bringing overcast skies. Cirrostratus, while also high clouds, are usually a thin layer that covers the sky and can create halos around the sun or moon but are not as high as cirrus. Altostratus clouds are mid-level clouds that can spread over a wide area and form between 6,500 and 20,000 feet, making them significantly lower than cirrus clouds.

This differentiation in altitude and characteristics makes cirrus clouds the highest type in this classification.