Cloud Formation and Fog

Question 1

How can condensation occur at less than 100% relative humidity?

Answer 1

Abundance of Condensation Nuclei

Question 2

What are the 5 processes which result in the ascent of air and adiabatic cooling?

Answer 2

1. Convection
2. Mechanical Turbulence
3. Frontal Lift
4. Orographic Lift
5. Convergence

Evaporation of falling rain and Advection over a colder surface

Question 3

What are the 4 families of clouds?

Answer 3

1. High Clouds
2. Middle Clouds
3. Low Clouds
4. Clouds of Vertical Development

Question 4

What family of clouds is based 20 000ft to 40 000ft?

Answer 4

High Clouds

Question 5

What family of clouds is based 6 500ft to 20 000ft?

Answer 5

Middle Clouds

Question 6

What family of cloud is based on the surface to
6 500ft?

Answer 6

Low Clouds

Question 7

What family of clouds is based 1 600ft up?

Answer 7

Clouds of Vertical Development

Question 8

This cloud appears as white curly streaks across the sky.

Answer 8

Cirrus (CI)

Question 9

This cloud appears as a whitish veil through which the sun and moon can be seen, often surrounded by a halo.

Answer 9

Cirrostratus (CS)

Question 10

This is a somewhat rare cloud. It appears as a white sheet with a pebbly pattern.

Answer 10

Cirrocumulus (CC)

Question 11

This is a layer cloud with no definite pattern. It is steely or bluish in colour and, as seen from a particular place, may cover the entire sky. Sometimes sun or moon can be seen through it but there are no halos.

Answer 11

Altostratus (AS)

Question 12

This is a layer or series of patches of rather flattened, rounded masses of cloud. The cloudlets may be arranged in groups, lines or waves and are sometimes so close that their edges join.

Answer 12

Altocumulus (AC)

Question 13

This cloud is pronounced with turrets building upward. It implies considerable instability in the cloud layer and may develop into cumulonimbus.

Answer 13

Altocumulus Castellanus (ACC)

Question 14

A uniform layer of very low cloud that may appear in extensive sheets or irregular patches.

Answer 14

Stratus (ST)

Question 15

This is the main precipitation cloud: continuous rain, snow, freezing rain, etc, may be encountered when flying in or below it. It is an extensive layer, uniformly dark in colour, based near or at the ground.

Answer 15

Nimbostratus (NS)

Question 16

The bottom of this cloud is clear-cut, wavy or rolled appearance. Appears as an extensive sheet, but sometimes well defined breaks between the rolls. It may give little precipitation.

Answer 16

Stratocumulus (SC)

Question 17

These are fluffy white clouds that form in the top of convective currents. Their edges are hard and clear-cut in appearance and their tops are rounded.

Answer 17

Cumulus (CU)

Question 18

Clouds that have grown considerable height but still have clear-cut rounded tops. Showers may fall from this.

Answer 18

Towering Cumulus (TCU)

Question 19

This cloud loses its hard, clear-cut appearance and frays our into a widespread, white, fibrous structure, often called an anvil or thunderhead. Heavy precipitation in the form of rain or hail showers may be seen pouring out of it.

Answer 19

Cumulonimbus (CB)

Question 20

ADF and LF radio interference occurs in this type of cloud.

Answer 20

High Clouds

Question 21

Infrared sensors are affected by this type of cloud.

Answer 21

Middle Clouds

Question 22

What determines whether the cloud forms in horizontal sheets (stratiform) or builds up in towers (cumuloform)?

Answer 22

The stability or instability of the air

Question 23

What is the major mechanism that causes condensation?

Answer 23

Adiabatic Expansion

Question 24

What is the word that is added to the names of clouds that normally produce precipitation?

Answer 24

Nimbus

Question 25

What determines the intensity of precipitation?

Answer 25

1. Strength of the updraft within the cloud
2. Cloud’s vertical thickness
3. Water content

Question 26

What are the 2 reasons for the importance of the vertical thickness of clouds?

Answer 26

1. Warm Air; Low Cloud Base
2. Ice crystals required; cloud top must be below freezing

Question 27

This precipitation is of short, duration, beginning and ending abruptly. Falls from cumuloform cloud.

Answer 27

Showery

Question 28

This precipitation is not showery, but has stopped and recommenced at least once during an hour. Falls from layer clouds.

Answer 28

Intermittent Precipitation

Question 29

This precipitation is not showery but continues without a break for at least an hour. Falls from layer clouds.

Answer 29

Continuous Precipitation