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PPL TC Meteorology > Clouds > Flashcards

Flashcards in Clouds Deck (27):
1

What are High clouds?

High cloud is cloud with a base above 20,000'. High clouds normally contain the word "cirro" or the word
cirrus

2

What is a Cirrus cloud?

Cirrus (Ci). Very high. Thin, wavy sprays of white cloud made up of slender, delicate curling wisps or fibres. Sometimes takes the form of feathers or ribbons or delicate fibrous bands. Often called cats’ whiskers or mares’ tails.

3

What is a Cirrocumulus cloud?

Cirrocumulus (Cc). Thin clouds, cotton or flake-like. Often
called mackerel sky. Gives little indication of future weather
conditions.

4

What is a Cirrostratus cloud?

Cirrostratus (Cs). Very thin high sheet cloud through which the
sun or moon is visible, producing a halo effect. Cirrostratus is
frequently an indication of an approaching warm front or
occlusion and therefore of deteriorating weather.

5

What is a Middle Cloud?

Middle cloud is cloud with a base between 6,500' and 20,000'. Middle clouds usually contain the word "alto"

6

What is an Altocumulus cloud?

Altocumulus (Ac). A layer or series of patches of rounded
masses of cloud that may lie in groups or lines. Sometimes
they indicate the approach of a front but usually they have
little value as an indication of future weather developments.

7

What is an Altocumulus Castellanus cloud?

Altocumulus Castellanus (Acc). Altocumulus with a turreted
appearance. Instability, turbulence and shower activity are
characteristic. Altocumulus castellanus may develop into
cumulonimbus.

8

What is an Altostratus cloud?

Altostratus (As). A thick veil of grey cloud that generally covers
the whole sky. At first, the sun or moon may be seen through
the cloud, but they disappear as the cloud gets thicker. The
presence of altostratus indicates the near approach of a warm
front. Some light rain or snow may fall from thick altostratus.
Icing may occur in this cloud.

9

What is a low cloud?

Low cloud is cloud with a base below 6,500'. Low clouds are normally described by their appearance and do not have a prefix added to their descriptions:

10

What is a Stratus cloud?

Stratus (St). A uniform layer of cloud resembling fog but not
resting on the ground. Drizzle often falls from stratus. When
stratus cloud is broken up by wind, it is called stratus fractus.

11

What is a Stratocumulus cloud?

Stratocumulus (Sc). A layer or series of patches of rounded
masses or rolls of cloud. It is very often thin with blue sky
showing through the breaks. It is common in high pressure
areas in winter and sometimes gives a little precipitation.

12

What is a Nimbostratus cloud?

Nimbostratus (Ns). A low layer of uniform, dark grey cloud.
When it gives precipitation, it is in the form of continuous rain
or snow. The cloud may be more than 15,000 feet thick. It is
generally associated with warm fronts.

13

What is a Clouds of vertical development?

Clouds of vertical development are cumulus clouds which as their name suggests, grow vertically into towering cumulus or cumulonimbus (thunderstorm) clouds. The bases of these clouds can be in the lower (below 6,500 feet) or middle (6,500 to 20,000 feet) and the tops can extend into the stratosphere in extreme cases

14

what is a Cumulus cloud?

Cumulus (Cu). Dense clouds of vertical development. They
are thick, rounded and lumpy and resemble cotton balls.
They usually have flat bases and the tops are rounded. They
cast dense shadows and appear in great abundance during
the warm part of the day and dissipate at night. When these
clouds are composed of ragged fragments, they are called

15

What is a Towering Cumulus cloud?

Towering Cumulus (TCu). Cumulus clouds that build up into
high towering masses. They are likely to develop into cumulonimbus. Rough air will be encountered underneath this cloud. Heavy icing may occur in this cloud type.

16

What is a Cumulonimbus cloud?

Cumulonimbus (Cb). Heavy masses of cumulus clouds that
extend well above the freezing level. The summits often
spread out to form an anvil shaped top that is characteristic
of thunderstorm and showery conditions. Violent vertical currents exist within the cloud.

17

Description of cloud coverage
What is Clear sky?

Clear - sky is clear below 10,000' as interpreted
by an autostation

18

Description of cloud coverage
What is SKC sky?

SKC - no clouds

19

Description of cloud coverage
What is Few cloud?

Few - clouds cover greater than zero & up to 2/8
of the sky

20

Description of cloud coverage
What is Scattered clouds?

Scattered - clouds cover between 3/8 and 4/8 of
the sky

21

Description of cloud coverage
What is Broken clouds?

Broken - clouds cover 5/8 or more of the sky up
to just less than 8/8

22

Description of cloud coverage
What is Overcast clouds?

Overcast - clouds cover 8/8 of the sky

23

What is CEILING?

CEILING: is the height of the base of the lowest broken or overcast layer of cloud

24

What is MIST and FOG?

Mist and fog are clouds at ground level. The difference between the two is a matter of visibility

25

What is the visibility in MIST?

In MIST visibility is 5/8 nm or greater

26

What is the visibility in FOG?

In FOG visibility is less than 5/8 nm

27

How do you find the ceiling altitude?

take the temp and minus the dew point to find the spread and then divide it by 2.5°C (3°C for transport Canada) and the times it by 1000