Weird and Wonderful of Nature: Cloud Formations

Weird and Wonderful of Nature: Cloud Formations

By Mr Ghaz, August 13, 2011

Image Credit

Weird and Wonderful of Nature: Cloud Formations

 

Image Credit

Clouds form when moisture in the atmosphere condenses into wear droplets.

Fog is, in effect, a type of ground-level cloud and also forms condensation.

Clouds are classified into two groups rounded clouds, known as cumulus, and layered clouds, known as stratus. Clouds are also categorized by the height at which they occur above the ground. They revealed what is going on at different levels in the atmosphere and what type of weather may be on the way.

A cloud’s appearance also depends on factors such as temperature and wind speed, which can produce a range of variations.

Cloud Formation

 

Image Credit

Clouds are formed by rising air. There are three main causes:

Convection: A hot land surface heats the air, causing pockets of warm air to rise. This usually results in cumulus clouds.

Frontal Cloud: Cold and warm fronts meet and the warm air is forced up. This usually results in stratus clouds.

Orographic Lifting: As air forced up the side of a mountain. This results in cumulus clouds.

As air rises, it cools. Cool air holds less water vapor than warm air, and it reaches a point when condensation takes place, forming water droplets or at high altitudes, ice crystals.

Fog

Image Credit

Officially, fog refers to conditions when visibility is no more than 1 km (0.6 miles). It forms from condensation close to the ground either when warmer and cooler air currents meet, or when warm air flows over a cold surface. Sea fogs form where cold and warm currents meet and the air above them mixes. The thickness of fog depends on the quantity of water particles in the air.

Cloud Varieties and Features

Image Credit

Terms used to describe and distinguish between the many variations on basic cloud types include:

Image Credit

Anvil/ Incus: A very tall, flat-topped cumulonimbus cloud- the characteristic shape of a thundercloud.

Image Credit

Castellanus: The upper part of the cloud has projections resembling battlements. Applies to cirrus and all types of cumulus clouds.

Image Credit

Cloud Street: Line of cumulus clouds formed parallel to wind direction.

Image Credit

Congestus: A vertical cumulus cloud with bulging upper parts.

Image Credit

Lenticular: Lens- shaped clouds that form over mountains. They remain relatively stationary.

Image Credit

Mackerel Sky: Cirrocumulus or small altocumulus clouds patterned like the scales of a mackerel.

Image Credit

Mother-of-Pearl: Wave clouds where light is diffracted into iridescent colors.

Image Credit

Noctilucent: Race, silvery luminous cloud seen on summer night in high altitudes.

Image Credit

Undulatus: Cloud that is undulating, or that has formed in waves.

Image Credit

CIRRUS: High-level clouds composed of minute specks of ice. They form in feathery white wisps, and are sometimes known as mare’s tails.

Image Credit

CIRROCUMULUS: High- level cloud that forms in small, rounded tufts, sometimes in a ‘mackerel sky’ pattern.

Image Credit

CIRROSTRATUS: High- level cloud that is stretched out in thin sheets.

Image Credit

ALTOCUMULUS: Mid- level cloud that is similar to cirrocumulus, with large tufts arranged in lines.

Image Credit

CUMULONIMBUS Have a flat base that occurs at around 1400m (4500ft). The top can extend to over 6km (20000ft).

Image Credit

STRATOCUMULUS: Low- level sheets of cloud that produce a dull, grey sky.

Image Credit

CUMULUS: Have a flat base and dome- shaped top. The base occurs at around 1400m (4500ft) and the top extends to bout 1800m (6000ft).

Common Cloud Types

Clouds are categorized by their shape and by the height at which they form.

Clouds that form in rounded heaps are called cumulus, and indicate unstable weather conditions.Clouds that form in flat layers are called stratus, and indicate stable conditions.

Clouds that form above 6000m (19500ft) are described by the prefix cirro- (or cirrus).

Clouds that form 2000m to 6000m (6500ft to 19500ft) are given the prefix alto- (or altus).

For clouds that occur below 2000m (6500ft), cumulus and stratus are used on their own.

Nimbus is used on its own, or in conjunction with other cloud names, and means ‘rain- bearing’.