Amazing And Rare Cloud Types

Amazing And Rare Cloud Types - 1 Mammatus Clouds

Amazing And Rare Cloud Types - 2 Lenticular Clouds

Amazing And Rare Cloud Types - 3 Undulatus Asperatus

Amazing And Rare Cloud Types - 4 Fallstreak Hole

Amazing And Rare Cloud Types - 5 Polar Stratospheric Cloud

Amazing And Rare Cloud Types - 6 Cirrus Kelvin-Helmholtz

Amazing And Rare Cloud Types - 7 Roll Clouds

Amazing And Rare Cloud Types - 8 Anvil Clouds

Clouds are classified into four basic categories, depending largely on the height of their bases above the ground.  High-level clouds, called cirrus clouds, can reach heights of 20,000 feet (6,000 meters) and are typically thin. They do not produce rain and often indicate fair weather. They are usually made up of ice.  Midlevel clouds form between 6,500 feet (2,000 meters) and cirrus level. They are referred to as "alto-" clouds and bear such names as altostratus or altocumulus, depending on their shape. (Altostratus clouds are flat; altocumulus clouds are puffy.) They frequently indicate an approaching storm. They themselves sometimes produce virga, which is rain or snow that does not reach the ground.  Low-level clouds lie below 6,500 feet (2,000 meters). Meteorologists refer to them as stratus clouds. They're often dense, dark, and rainy (or snowy) though they can also be cottony white clumps interspersed with blue sky.