Met - Formation Of Clouds And Precipitation

Front 1

In what states can water exist?

Back 1

Solid (ice), liquid and gas (water vapour)

Front 2

Can water exist as a liquid below 0ºC?

Back 2

Yes, super-cooled water

Front 3

What does water need to crystallise?

Back 3

a condensation nucleus

Front 4

What happens when water vapour changes to a liquid or solid?

Back 4

Deposition and condensation - give off latent heat

Front 5

What happens when water changes from liquid or solid to a vapour?

Back 5

Evaporation and sublimation - absorb latent heat

Front 6

What happens when water changes from a liquid to a solid?

Back 6

Freezing - give off latent heat

Front 7

What happens when water changes from a solid to a liquid?

Back 7

Melting - absorbs latent heat

Front 8

What is the amount of water in the air dependant on?

Back 8

Evaporation

Front 9

What is a parcel of air called when it can not hold anymore water vapour in it?

Back 9

Saturated

Front 10

What is relative humidity?

Back 10

A percentage of the maximum

Front 11

What is the relative humidity when a parcel of air is saturated?

Back 11

100%

Front 12

What is the dewpoint?

Back 12

The temperature that a parcel of air when cooled at constant pressure will become saturated

Front 13

What will be the result of further cooling of the air?

Back 13

Condensation

Front 14

Does dewpoint decrease or increase with height and at what rate?

Back 14

Decreases with height - at about 1/2º per 1000ft

Front 15

Why does dewpoint decrease with height?

Back 15

due to pressure decrease

Front 16

What is the Adiabatic Process?

Back 16

A temperature change as a result of pressure changes, even though heat energy is neither added to nor taken from the system.

Front 17

What does expanding a gas and decreasing its pressure cause?

Back 17

A lowering of temperature

Front 18

How are clouds formed?

Back 18

A parcel of moist air is forced to rise, cools and the water vapour contained within the parcel of air condenses

Front 19

What 3 main groups do clouds belong to?

Back 19

Stratiform, Cumuloform and Cirroform

Front 20

What are Stratiform clouds like?

Back 20

Flat or sheet-like

Front 21

What are Cumuloform clouds like?

Back 21

Heaped or towering in appearance

Front 22

What are Cirroform clouds like?

Back 22

Appear wispy

Front 23

Where is a cloud level measured from?

Back 23

The base of the cloud

Front 24

What are the characteristics of high level clouds?

Back 24

- detached clouds of white filaments
- patches or bands
- formed by widespread lifting
- composed entirely of ice crystals

Front 25

Which types of clouds are at high levels?

Back 25

Cirrus, Cirrostratus and Cirrocumulus

Front 26

What type of cloud is:
Detached clouds in the form of white, delicate filaments, or white or mostly white patches or narrow bands. These clouds have a fibrous (hair-like) appearance, or a silky sheen, or both.

Back 26

Cirrus (Ci)

Front 27

What type of cloud is:
Transparent, whitish cloud veil of fibrous (hair-like) or smooth appearance, totally or partly covering the sky, and generally producing a halo phenomenon.

Back 27

Cirrostratus (Cs)

Front 28

What type of cloud is:
Thin, white layer, sheet or patch of cloud without shading, composed of very small elements in the form of grains, ripples, etc., merged or separate, and more or less regularly arranged. Most of the elements have an apparent width of less than one degree.

Back 28

Cirrocumulus (Cc)

Front 29

What is involved in the formation of Cirrocumulus?

Back 29

Turbulence or perturbations, usually in pre-existing Ci or Cs.

Front 30

What are the characteristics of medium level clouds?

Back 30

- greyish or bluish
- sun may be just visible
- composed predominately of supercooled water

Front 31

Which types of clouds are at medium levels?

Back 31

Altostratus, Altocumulus, Nimbostratus and Lenticular

Front 32

What conditions create Lenticular clouds?

Back 32

An altostratus with lower humidity near mountain ranges, only associated with mountain waves.

Front 33

What cloud type is:
Greyish or bluish cloud sheet or layer of striated, fibrous or uniform appearance, totally or partly covering the sky, and having parts thin enough to reveal the sun at least vaguely, as if through ground glass. Altostratus does not show halo phenomena.

Back 33

Altostratus

Front 34

What cloud type is:
White or grey, or both white and grey patch, sheet or layer of cloud, generally with shading, composed of laminae, rounded masses, rolls, etc. which are sometimes partly fibrous or diffuse, and which may or may not be merged. Most of the regularly arranged small elements usually have apparent width of between one and five degrees.

Back 34

Altocumulus

Front 35

What cloud type is:
Grey cloud layer, often dark, the appearance of which is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground. It is thick enough to blot out the sun.

Back 35

Nimbostratus

Front 36

What are the characteristics of low-level clouds?

Back 36

- sheet-like stratiform clouds
- fluffy cumuliform clouds
- mix of both
- clouds of considerable vertical extent
- composed of water, supercooled water and/or ice

Front 37

Which types of clouds are at low levels?

Back 37

Stratus, stratocumulus, cumulus, towering cumulus, cumulonimbus and mammatus

Front 38

What type of cloud is:
Grey or whitish, or both grey and whitish, patch, sheet or layer of cloud which almost always has dark parts composed tessellations, rounded masses, rolls, etc., which are non-fibrous (except for virga), and which may or may not be merged. Most of the regularly arranged small elements have an apparent width of more than five degrees.

Back 38

Stratocumulus (Sc)

Front 39

What type of cloud is:
Generally grey cloud layer with a fairly uniform base, which may give drizzle, ice prisms or snow grains. When the sun is visible through the cloud, its outline is clearly discernible. Stratus does not show halo phenomena, except possible at very low temperatures. Sometimes stratus appears in the form of ragged patches.

Back 39

Stratus (St)

Front 40

What type of cloud is:
Detached clouds, generally dense and with sharp outlines, developing vertically in the form of rising mounds, domes or towers, of which the bulging upper part often resembles a cauliflower. The sunlit parts of these clouds are a most brilliant white. Their base is relatively dark and nearly horizontal. Sometimes cumulus is ragged.

Back 40

Cumulus (Cu)

Front 41

What type of cloud is:
Heavy and dense cloud, with a considerable vertical extent in the form of a mountain or huge towers. At least part of its upper portion is usually smooth, or fibrous or striated and nearly always flattened. This part often spreads out in the shape of an anvil or vast plume.

Back 41

Cumulonimbus (Cb)