Where are the bases of cumulus or cumulonimbus clouds typically located?

The bases of cumulus and cumulonimbus clouds are typically found at low to middle cloud heights, generally ranging from just above the surface up to about 6,500 to 20,000 feet, depending on atmospheric conditions. Cumulus clouds, which are often puffy and white, start forming when warm air rises, and their bases are usually around 1,000 to 3,000 feet above ground level. Cumulonimbus clouds, known for their towering structure and association with thunderstorms, can have bases that are similarly low but extend high into the atmosphere as they develop.

This understanding is key because it shows how these clouds are influenced by surface heating and the subsequent lifting of air parcels. Other options do not accurately reflect the typical altitudes at which these cloud types form. High altitudes only suggests a level that does not apply to the bases of these clouds, while locating them only at surface level ignores the necessary upward motion of air. Stating that they form only above 10,000 feet disregards the full range of cloud bases, especially for cumulus clouds, which typically start at lower levels. The correct option acknowledges the most common altitudinal range for these cloud types.