Clouds

Question 1

What are the four families of clouds?

Answer 1

High, middle, low, and clouds of vertical development.

Question 2

What are high clouds composed of?

Answer 2

Ice crystals.

Question 3

What are middle clouds composed of?

Answer 3

Water droplets or ice crystals, possibly supercooled.

Question 4

What are low clouds composed of?

Answer 4

Water droplets, supercooled droplets, and sometimes ice crystals.

Question 5

What does “nimbus” indicate in a cloud name?

Answer 5

That the cloud produces precipitation.

Question 6

What is the base height range of high clouds in temperate regions?

Answer 6

16,500 to 45,000 ft.

Question 7

What is the base height of middle clouds in temperate regions?

Answer 7

6,500 to 23,000 ft.

Question 8

What is the base height of low clouds in temperate regions?

Answer 8

Surface to 6,500 ft.

Question 9

What are cirrus clouds (Ci)?

Answer 9

High, wispy clouds often called cat’s whiskers or mares’ tails.

Question 10

What are cirrocumulus clouds (Cc)?

Answer 10

Flake-like high clouds, sometimes called “mackerel sky.”

Question 11

What are cirrostratus clouds (Cs)?

Answer 11

Thin sheet clouds producing halos, indicating a warm front.

Question 12

What are altocumulus clouds (Ac)?

Answer 12

Patches of rounded masses in lines or groups, little weather significance.

Question 13

What are altocumulus castellanus (Acc)?

Answer 13

Turreted Ac clouds indicating instability and possible showers.

Question 14

What are altostratus clouds (As)?

Answer 14

Grey veil-like clouds that thicken and may produce light rain or snow.

Question 15

What is stratus (St)?

Answer 15

Uniform low cloud layer resembling fog; may produce drizzle.

Question 16

What is stratus fractus (Sf)?

Answer 16

Stratus cloud broken by wind.

Question 17

What is stratocumulus (Sc)?

Answer 17

Patches or rolls of low clouds with blue sky visible between.

Question 18

What is nimbostratus (Ns)?

Answer 18

Thick dark grey cloud producing continuous rain or snow.

Question 19

What are cumulus clouds (Cu)?

Answer 19

Puffy cotton-like clouds with flat bases and rounded tops.

Question 20

What is cumulus fractus (Cf)?

Answer 20

Ragged fragments of cumulus clouds.

Question 21

What is towering cumulus (TCu)?

Answer 21

Large cumulus indicating potential for cumulonimbus formation.

Question 22

What is cumulonimbus (Cb)?

Answer 22

Thunderstorm cloud with anvil top, causing severe weather.

Question 23

What does “clear” mean in METAR terms?

Answer 23

0 oktas of cloud cover.

Question 24

What does “few” mean?

Answer 24

2 oktas or less.

Question 25

What does “scattered” mean?

Answer 25

3 to 4 oktas.

Question 26

What does “broken” mean?

Answer 26

5 to 7 oktas.

Question 27

What does “overcast” mean?

Answer 27

8 oktas.

Question 28

What is condensation?

Answer 28

When water vapor turns into droplets as the air cools.

Question 29

What is the condensation level?

Answer 29

The altitude where condensation begins — cloud base.

Question 30

What are condensation nuclei?

Answer 30

Particles like dust or salt that water droplets form on.

Question 31

What is deposition?

Answer 31

Water vapor turning directly into ice crystals.

Question 32

What are supercooled water droplets?

Answer 32

Liquid water existing below 0°C.

Question 33

What are the two main ways clouds form?

Answer 33

1) Air is cooled to saturation; 2) More water vapor is added until saturation.

Question 34

What is adiabatic cooling?

Answer 34

Cooling of air as it expands when lifted.

Question 35

How does stability affect cloud shape?

Answer 35

Stable air → stratus; unstable air → cumulus.

Question 36

What is orographic lift?

Answer 36

Air forced to rise over hills or mountains, cooling and forming clouds.

Question 37

What clouds form with moist stable air and orographic lift?

Answer 37

Stratus.

Question 38

What clouds form with moist unstable air and orographic lift?

Answer 38

Cumulus or cumulonimbus.

Question 39

What is convection?

Answer 39

Rising warm air that cools and condenses into clouds.

Question 40

What determines the height of convection clouds?

Answer 40

Stability of the air and mid-level atmosphere.

Question 41

What clouds are associated with a warm front?

Answer 41

Cirrus → altostratus → nimbostratus.

Question 42

What clouds are associated with a cold front?

Answer 42

Cumulus and cumulonimbus.

Question 43

What causes mechanical turbulence?

Answer 43

Wind over a rough surface.

Question 44

What clouds form from mechanical turbulence?

Answer 44

Stratocumulus; if moist and unstable, cumulus.

Question 45

What is an inversion?

Answer 45

A layer where temperature increases with height, blocking vertical motion.

Question 46

What is convergence?

Answer 46

Air piling up, forced to rise and form clouds.

Question 47

Where does convergence commonly occur?

Answer 47

In low-pressure areas and along fronts.

Question 48

Why should pilots avoid cumulonimbus clouds?

Answer 48

Due to turbulence, hail, icing, and thunderstorms.

Question 49

Which cloud type can make VFR operations difficult?

Answer 49

Stratus, due to low ceilings and poor visibility.

Question 50

What indicates approaching warm fronts in high/middle clouds?

Answer 50

Cirrostratus and altostratus.