A cloud is a mass of water drops or ice crystals suspended in the atmosphere. Clouds form when water condenses in the sky. The condensation lets us see the water vapor. There are many different types of clouds. Clouds are an important part of Earth’s weather and climate.
A cirrus cloud is a high-altitude, wispy, and delicate cloud formed entirely of ice crystals, often appearing as white filaments or feathery streaks. Derived from the Latin word for "curl of hair," they typically signify fair weather but can also signal the approach of a warm front or a low-pressure area.
Cirrostratus clouds are transparent, high-altitude, thin, sheet-like clouds composed of ice crystals that often cover the entire sky and are distinguished by producing a halo phenomenon around the Sun or Moon. These clouds appear as a whitish, veil-like layer, which can have a smooth or fibrous (hair-like) appearance, but they are generally thin enough that the Sun's disc remains visible and shadows are cast on the ground. Cirrostratus clouds are often the first sign of an approaching weather front and can signal that steady precipitation is expected in the next 12 to 24 hours.
Cirrocumulus clouds are high-altitude clouds made of ice crystals that appear as a thin, white layer of small, rounded, puffy cloudlets arranged in rows or ripple-like patterns, sometimes resembling the scales of a fish ("mackerel sky"). They are generally associated with fair, cold weather and are less than one degree apparent width, or smaller than a finger held at arm's length.
An altocumulus cloud is a mid-level cloud that appears as patchy, layered, or wavy masses of rounded clumps, rolls, or plates. Named from Latin for "high" and "heap," they form between 7,000 and 20,000 feet and are composed of a mix of water and ice, giving them a slightly more ethereal appearance than lower-level cumulus clouds. While generally associated with settled weather, they can sometimes signal atmospheric instability or an approaching warm front.
A cumulonimbus cloud is a large, dense, and tall storm cloud that forms as a result of strong vertical development. Also known as thunderclouds, they are characterized by a dark base and can extend high into the sky, often forming a distinctive flat, anvil-shaped top. These clouds are associated with heavy precipitation, lightning, thunder, and potentially severe weather such as hail, strong winds, and tornadoes.
Stratocumulus clouds are low-level clouds appearing as large, rounded, white or grayish masses that form in groups, rolls, or waves, often with darker patches and gaps of blue sky in between. They have a lumpy, lumpy appearance due to weak convection, are typically composed of water droplets, and are the most common clouds on Earth. While they can cover the sky, they are generally associated with dry weather and rarely produce more than light drizzle.
A cumulus cloud is a detached, individual, cauliflower-shaped cloud with a flat base and puffy, rounded tops, formed by the convection of rising warm, moist air. Often seen in fair weather and appearing as fluffy white cotton balls, their name comes from the Latin word "cumulus," meaning "heap" or "pile". These low-level clouds can grow vertically, developing into towering cumulus congestus or even cumulonimbus clouds (thunderstorms) if atmospheric conditions are unstable.
