Then the clouds are grouped by shape and how high they can be found in the sky. Hence, we define them as:
- Low-level clouds: cumulus, stratus, and stratocumulus
- Middle clouds: altocumulus, nimbostratus, and altostratus
- High-level clouds: cirrus, cirrocumulus, and cirrostratus
- Cumulonimbus clouds rise across the low, middle, and upper atmosphere.
One could add fog as a shallow layer of cloud that is closer to the ground. It makes for an eerie feeling to drive through fog, especially when driving up or down a hill, and you enter it to leave it behind. Same as when a plane dives into or climbs above clouds. All these forms are essentially made of water droplets and ice crystals and their shapes depend on how moist is the air, what atmospheric pressure surrounds them, and their condensation. An amazing sight is the one of clouds hurled by the wind, changing shapes, or even at times dissolving into thin air. Light from the sun, and at times the moon, passes through the clouds. When it doesn't because of their thickness, the clouds appear to be grey or of a darker shade.