Cloud

A cloud is a visible mass of condensation droplets or ice crystals suspended in the atmosphere above the surface of the Earth or another planetary body.

Cloud Classification

Clouds are divided into two general categories: layered and convective. These are named stratus clouds (or stratiform, the Latin stratus means layer) and cumulus clouds (or cumiloform, cumulus means piled up). These two cloud types are divided into four more groups that distinguish the cloud's altitude. Clouds are classified by the cloud base height, not the cloud top. This system was proposed by Luke Howard in 1802 in a presentation to the Askesian Society.

Related Topics:
Stratus cloud - Cumulus cloud - Luke Howard - 1802 - Askesian Society

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

High clouds (Family A)

These generally form above 16,500 feet (5,000 m), in the cold region of the troposphere. However, in Polar regions they may form as low as 10,000 ft (3,048 m). They are denoted by the prefix cirro- or cirrus. At this altitude water almost always freezes so clouds are composed of ice crystals. The clouds tend to be wispy, and are often transparent.

Related Topics:
M - Troposphere - Polar - Cirrus - Ice crystal

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clouds in Family A include:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Cirrus
• Cirrus uncinus
• Cirrus Kelvin-Helmholtz
• Cirrostratus
• Cirrocumulus
• Pileus
• Contrail

A contrail is a long thin cloud which develops as the result of the passage of a jet airplane at high altitudes.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Middle clouds (Family B)

These develop between 6,500 and 16,500 feet (between 2,000 and 5,000 m) and are denoted by the prefix alto-. They are made of water droplets, and are frequently supercooled.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clouds in Family B include:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Altostratus
• Altostratus undulatus
• Altocumulus
• Altocumulus undulatus
• Altocumulus mackerel sky
• Altocumulus castellanus
• Altocumulus lenticularis

Low clouds (Family C)

These are found up to 6,500 feet (2,000 m) and include the stratus (dense and grey). When stratus clouds contact the ground they are called fog.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clouds in Family C include:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Stratus
• Nimbostratus
• Cumulus humilis
• Cumulus mediocris
• Stratocumulus

Vertical clouds (Family D)

These clouds can have strong upcurrents, rise far above their bases and can form at many heights.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Clouds in Family D include:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Cumulonimbus (associated with heavy precipitation and thunderstorms)
• Cumulonimbus incus
• Cumulonimbus calvus
• Cumulonimbus with mammatus
• Cumulus congestus
• Pyrocumulus

Other clouds

A few clouds can be found above the troposphere; these include nacreous, noctilucent and polar stratospheric clouds which occur in the stratosphere and mesosphere respectively.

Related Topics:
Troposphere - Nacreous - Noctilucent - Polar stratospheric clouds - Stratosphere - Mesosphere

~ ~ ~ ~ ~ ~ ~ ~ ~ ~