Cloud is a visible mass of condensed water vapor or frozen crystals suspending in the air. When there's an amount of droplets in the air, it become visible as clouds. Dense Deep clouds exhibit a high reflectance, about 70-95% throughout the visible wavelength, thus they appear white. Cloud droplets tend to absorb light rays, therefore dense clouds appear dark on its bottom.

When air is cooled below its saturation point, water vapor condense to larger molecules and form clouds. The water in typical cloud can weigh up to several million tonnes. The Volume of a cloud is big and the density is low enough such that warm air holding the droplets is sufficient to keep the cloud suspended. The water vapors and constantly re-evaporating inside the cloud and creating an updraft. When the droplets are too large (Caused by continuous collision of water vapors) they overcome the updraft and air movements around them and fall as rain.

Clouds are divided into 2 main categories, Layered and Convective. They are named "Stratus Clouds" and "Cumulus Clouds". Stratus, in Latin, Means "Layer" while Cumulus means "Piled Up". These 2 cloud types are divided into 4 groups that distinguish the cloud's altitude. Clouds are classified by its base height, not its top.

High Clouds (Family A)
These clouds generally form above 6,000 m, in the cold region of the Troposphere. At this altitude, water freezes and so the clouds are mainly composed of ice crystals. They are usually wispy and transparent. These clouds are denoted by the prefix "Cirro-" or "Cirrus".
- Cirrus (Ci) : These clouds are composed of Ice Crystals and are characterized by thin, wisplike strands,
often accompanied by tufts. Cirrus usually form above altitude of 8,000 m.
- Cirrostratus (Cs) : These clouds form above 6,000 m and often produce Halos. They appear whitish, usually covers the whole sky and sometimes so thin as to be hardly discernible.
- Cirrocumulus (Cc) : Like other Cumulus, These clouds signify convection. Unlike other Cirrus Clouds, these clouds contain supercooled water droplets instead of ice crystals. Ice crystals are also present, and causing the water droplets to rapidly freezes and transform into Cirrostratus. Thus Cirrocumulus are short-lived.

Middle Clouds (Family B)
These clouds develop between an altitude of 2,000 to 5,000 m and are denoted by a prefix "-alto". They are made of water droplets and are frequently supercooled.
- Altostratus (As) : They appears as a uniform gray sheet of layer, often covering the whole sky. They are lighter than Nimbostratus but darker than Cirrostratus. The cloud are caused by a large air mass that is lifted and then condensed.
- Altocumulus (Ac) : Cloud that are characterized by globular masses or rolls in layers or patches. They are darker than Cirrocumulus. One form of Altocumulus, the Altocumulus Lenticularis are often mistaken as "Unidentified Flying Objects (UFOs)".

Low Clouds (Family C)
From sea level up to 2,000 m is where these clouds are formed. They are usually denser. When Stratus clouds contact the floor, they are called Fog.
- Stratus (St) : Stratus Clouds are uniform base, featureless clouds that often covers a wide area, like other stratus clouds. This Stratus cloud can develop into a Nimbostratus cloud.
- Stratocumulus (Sc) : These clouds belongs to a class characterized by large dark, rounded masses, and usually in groups. They form below 2,400 m. Weak convective currents create shallow clouds because of drier current above the clouds preventing its vertical development.
- Cumulus Mediocris (Cu) : Cumulus Mediocris is slightly larger in vertical development than Cumulus Humilis clouds. They may further advance into larger Cumulus Clouds.

Vertical Clouds (Family D)
These clouds can have strong updrafts, rise far above their bases and form at many heights.
- Cumulonimbus (Cb) : They are tall, dense and associates with thunderstorms and other intense weather. They can form alone or in clusters. They can further develop into a Supercell, the largest and most severe class of thunderstorms. The three ingredients that produces these clouds are, Plenty of Moisture, A Mass of Warm, Unstable Air, and A Source of Energy to Lift the Mass of Air Rapidly Upwards. While the mass of warm air rises, it condenses rapidly due to the surrounding. This releases latent heat and heat up the surrounding. The water droplets continue to cools to form ice crystals. These ice crystals are heavy, they fall and creating a downward movement to compete with the updraft. This instability causes static electrical charge and thus Cumulonimbus are usually associated with Thunderstorms and Lightnings. The base of a Cumulonimbus can be several miles across, though formed at an altitude of about 3,000 to 4,000 m, its peak can reach up to 23,000 m in extreme cases. Typically, it peaks at a much lower height (usually up to 5,000 m).

Cloud Classification






Altocumulus Undulatus

Altocumulus Lenticularis

Stratus (From Top)


Cumulus Mediocris

Cumulus Humilis


© Maciejewski

1 comment:

  1. Please copyright my supercell photo. © Maciejewski