1. 5.04 Clouds and Fog References: FTGU pages 124-126, 147
Meteorology
5.04 Clouds and Fog
References:
FTGU pages , 147

2. 5.04 Clouds and Fog MTPs: Cloud Classification Types and Recognition
Associated Precipitation
Fog Formation and Types

3. Cloud Classification Height Shape and Clouds are classified by:
Families
Type/Way They Form

4. Cloud Classification
Two Cloud TYPES:
Stratus
Cumulus

5. Cloud Classification Four Cloud FAMILIES: High (Cirro) Middle (Alto)
bases between and feet
Ice crystals
Middle (Alto)
Bases between 6500 and feet
Ice crystals, water droplets
- Low (Strato)
Bases from surface to 6500 feet
- Clouds of Vertical Development
May form as low as 1500 feet
Water droplets above freezing

6. Cloud Classification

7. Types and Recognition High Clouds 1. Cirrus (Ci)
very thin wispy cloud, like it was made with an artist’s brush
sometimes referred to as cats’ whiskers or mares’ tail
generally no particular significance to flying

8. Types and Recognition High Clouds 2. Cirrocumulus (Cc)
thin cotton like clouds
looks like pattern of the sand at a beach
no indication of future weather conditions

9. Types and Recognition High Clouds 3. Cirrostratus (Cs)
thin high sheet of cloud
sun or moon is visible, producing a halo effect
often indicate an approaching warm front or occlusion and therefore of deteriorating weather conditions

10. Types and Recognition Mid level clouds 1. Altocumulus (Ac)
layers of rounded masses of cloud that may lie in groups or lines
sometimes associated with an approaching front but usually they have little value as a weather predictor

11. Types and Recognition Mid level clouds
2. Altocumulus Castellanus (Acc)
altocumulus with turreted edges
may develop into cumulonimbus
a variation of AC with greater vertical extent
characteristics include: instability, turbulence and shower activity

12. Types and Recognition Low Clouds 1. Status (St)
uniform layer of low cloud resembling fog but is not touching the ground
low visibility, drizzle and fog often associated

13. Types and Recognition Low Clouds 2. Stratocumulus (Sc)
layer or series of rounded masses or rolls of cloud
common in high pressure areas in winter
sometimes gives a little precipitation

14. Types and Recognition Low clouds 3. Nimbostratus (Ns)
‘Nimbo’ – means precipitation is associated with the cloud
low dark grey layer
thickened altostratus
associated with warm fronts and continuous/steady rain or snow
may be more than 15,000 ft thick
VFR operations often difficult to impossible

15. Types and Recognition Clouds of vertical development 1. Cumulus (Cu)
Dense, thick, rounded and lumpy
resembles cotton balls
flat bases and sharp clear cut surfaces
forming during day and dissipate at night
height of base depends on temperature and dew point spread
light to moderate turbulence
NO PRECIPITATION

16. Types and Recognition Clouds of Vertical Development
2. Towering Cumulus (TCu)
a development of cumulus cloud
serious (moderate to heavy) icing and turbulence
rain showers and snow showers in winter
rough air underneath

17. Types and Recognition Clouds of Vertical Development
3. Cumulonimbus (Cb)
development of TCU
often anvil shape top
produces lightning and thunder
gusty surface winds in vicinity
hail is often present within the cloud and may occasionally fall from it
heavy icing, turbulence and showers
may be embedded in stratiform clouds
cloud should be avoided

18. Confirmation
Name these clouds:

19. Precipitation Precipitation Cloud Type
Drizzle, Freezing drizzle, Snow grains
Stratus and Stratocumulus
Snow or Rain (continuous)
Thick Altostratus and Nimbostratus
Snow or Rain (intermittent)
Thick Altostratus and Stratocumulus
Snow Showers or Rain Showers
Altocumulus, Towering Cumulus and Cumulonimbus
Snow Pellets, Hail, Ice Pellets Showers
Cumulonimbus
Ice Pellets (continuous)
Any cloud that gives Rain - (below freezing)
Ice Prisms
No cloud necessary

20. Fog Formation and Types
Fog is:
Cloud (usually stratus) in contact with ground
Formed when:
Air cooled to due point
Air becomes saturated (moisture added)

21. Fog Formation and Types
Formed By Cooling
Formed by Adding Moisture
Radiation Fog
Steam Fog
Advection Fog
Ice Fog
Upslope Fog
Precipitation-Induced Fog

22. Fog Formation and Types
1. Radiation Fog (ground fog)
Forms at night
Initial heating from sun causes turbulence
Ground cools losing heat through radiation
Air in direct contact is cooled
Clear skies, moist air, light winds (2-5 knots)

23. Fog Formation and Types
2. Advection Fog
When warm moist air moves over a colder land or sea surface
Winds >15 knots
Most frequent in costal regions
Widespread when moist air from warm region of ocean moves over colder water

24. Fog Formation and Types
Precipitation Induced Fog (frontal fog)
Addition of moisture to air through evaporation of rain or drizzle
The precipitation from warm air evaporates and saturates cooler air below
Associated mostly with warm fronts

25. Fog Formation and Types
4. Upslope Fog
Cooling of air due to expansion as it move sup slope
Light upslope wind required

26. Fog Formation and Types
Steam Fog
Cold air passes over warm water surface
Evaporation of water into air until saturated
Occurs over rivers and lakes, especially during autumn

27. Fog Formation and Types
Ice Fog
Moist air during extremely cold calm conditions
The cold air cannot hold more moisture and excess sublimates into ice crystals
Crystals appear suddenly when engine started
Water vapour
Condensation nuclei
Mixing agent

28. Confirmation Watch the link: What clouds can you name?
What clouds can you name?

29. Confirmation What are the names for the 3 levels of clouds?
Name one type of cloud of vertical development.
What requirements are needed to create fog?
What type of precipitation would you get in:
i) stratus clouds
Ii) cumulus clouds

30. Nacreous Clouds may be found above the poles, and are actually in the Stratosphere