Cloud Classification Flashcards

1
Q

What can clouds indicate to pilots?

A

Turbulence, Icing, Poor visibility, windshear, wind direction, wind direction, Tropopause level

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2
Q

Why do clouds form?

A

When air becomes cooled to dew point
and/or
Evaporation causing air to saturate (above a water source etc)

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3
Q

Give the definition of Adiabatically

A

Adiabatically is a process that occurs without the exchange of heat energy.

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4
Q

How does air cool Adiabatically?

A

Air cools Adiabatically, due to expansion - as it rises through lower pressure within the upper troposphere.
(the lower pressure allows the air molecules to spread out)

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5
Q

What is the Dry Air Lapse Rate (DALR)?

A

DALR = 3°C / 1000ft

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6
Q

What is the Saturated Air Lapse Rate (SALR)?

A

SALR = 0.5°C / 1000ft

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7
Q

What is the Saturated Air Cooling Rate (SALR)?

A

SALR = 1.8°C / 1000ft

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8
Q

Give examples of condensation nuclei

A

Dust, smoke, bacteria, algae, sand, salt crystals, clay, soot, plankton, sulphates from volcanoes

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9
Q

What are the sizes of the average: rain drop, cloud droplet, condensation nuclei?

A

Rain drop = 2 mm

Cloud droplet = 0.02 mm

Condensation nuclei = 0.0002 mm

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10
Q

What is the equation to calculate cloud base?

A

Cloud base = 400 (Ta - Td)

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11
Q

What are the 5 ways that air is lifted?

A
Convection
Turbulence
Frontal lift
Orographic lift
Convergence
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12
Q

Give a basic description of a Stratus cloud

A

Generally flat + low

Wide, but not tall

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13
Q

Give a basic description of a Cumulus cloud

A

Tall + low
But not very wide

Have a ‘cauliflower’ appearance

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14
Q

Give a basic description of a Cirrus cloud

A

Fibrous + wispy

With a high altitude

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15
Q

Give the definition of a cloud base

A

The height above ground, of the lowest cloud (ft)

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16
Q

Give the definition of Cloud ceiling

A

Height above ground, of the lowest cloud layer - covering over half of the sky (4 oktas)

17
Q

Give the definition of Cloud top

A

The altitude of the top of the clouds, in FL or Ft

Low level clouds in Ft

18
Q

List the cloud coverage scales - including abbreviations and numerical value

A
0 = Sky clear (SKC)
1-2 = Few (FEW)
3-4 = Scattered (SCT)
5-7 = Broken (BKN)
8 = Overcast (OVC)
9 = Sky obscured (cannot see - fog/smoke)
19
Q

How does convection form clouds?

A

Air rising cools at DALR, until Ta = Td —- forming clouds (base)
Then still, cooling at SALR, until Ta = Td again —- no clouds (top)

20
Q

How does turbulence form clouds?

A

Air flowing over a rough surface, or thermal lifting - can result in a turbulent layer of air at around 3000ft (friction layer)
Air mixing with this layer results in an inversion forming. Near the top of this layer, the air is cooled to dew point - and clouds form.

Generally forming Stratocumulus (with light turbulence within)

21
Q

What are the high categories of clouds?

A

Low level —— No prefix —— Surface - 6500ft

Medium level —— Alto —— 6500 - 23000ft

High level —— Cirro —— 16000 - 45000ft

22
Q

How does the climate region affect cloud levels?

A

Within a tropical climate:

High level — Base and top rise
Medium level — Top rises
Low level — No effect

23
Q

What are the 10 different cloud genera?

Give with increasing height

A

All level = Cumulonimbus, Nimbostratus

Low level = Stratus, Cumulus, Stratocumulus

Mid level = Altostratus, Altocumulus

High level = Cirrostratus, Cirrocumulus, Cirrus

24
Q

Give the abbrev. for all level clouds

A

Cumulonimbus = CB

Nimbostratus = NS

25
Q

Give the abbrev. for low level clouds

A

Stratus = ST

Cumulus = CU

Stratocumulus = SC

26
Q

Give the abbrev. for mid level clouds

A

Altostratus = AS

Altocumulus = AC

27
Q

Give the abbrev. for high level clouds

A

Cirrostratus = CS

Cirrocumulus = CC

Cirrus = CI

28
Q

What are the 5 species of cloud?

A

Castellanus — Turreted (like castle towers)

Lenticularis — Lentil-like (wide, round top, flat bottoms)

Fractus — Broken

Humilis — Small, fair weather

Congentus — Heaped, towering

29
Q

Name the supplementary features

A
Anvil —- hammer top (Capillatus - when ‘hairs’ from this)
Mammatus —- udders
Virga —- rain not reaching the ground
Roll —- cylinder-like 
Tornado —- waterspout if in water
Towering
30
Q

What are the 2 methods of measuring cloud base?

A

Ceilometer —- laser, or light source used to measure cloud height

(Can also use satellite observations - through infrared or triangulation)

31
Q

What is the abbrev. for a Significant weather chart?

A

SIGWX

32
Q

What are the 5 categories used to measure amount of cloud on a SIGWX?

A
ISOL - isolated
OCNL - occasional 
FRQ - frequent
EMBD - embedded
WDSPD - widespread