1. Atmospheric Moisture and Cloud Formationby
Colleen Rae
Regional Training Centre

2. Atmospheric moisture Water vapour is an important atmospheric gas
Water Vapour is the source of moisture for:-
cloud development
resultant precipitation in solid and liquid forms
Composition of the Atmosphere
Nitrogen (N2) %
Oxygen (O2) %
Argon (Ar) %
Water vapor (H2O)
Carbon dioxide (CO2)
Neon (Ne)
Helium (He) %
Krypton (Kr)
Hydrogen (H)
Ozone (O3)
Document Reference: RTC-PRE Date of last revision: 22 August 2017

3. Atmospheric moisture <1% Water vapor (H2O)
MESOPAUSE
STRATOPAUSE
TROPOPAUSE
THERMOSPHERE
MESOSPHERE
STRATOSPHERE
100 90 80 70 60 50 40 30 20 10 KM oC
TROPOSPHERE
<1%
Water vapor (H2O)
Carbon dioxide (CO2)
Neon (Ne)
Helium (He)
Krypton (Kr)
Hydrogen (H)
Ozone (O3)
Within the first 6 km of the troposphere
Document Reference: RTC-PRE Date of last revision: 22 August 2017

4. Cloud appearance Cloud shapes and forms are the expression of
the way in which the air has risen,
their height above the ground,
if they are composed of water or ice crystals
the location of the sun
Cloud size is influenced by
heat
seasons
bodies of water
mountain ranges
condensation nuclei
Document Reference: RTC-PRE Date of last revision: 22 August 2017

5. How the atmosphere gets saturated
Convective development
Document Reference: RTC-PRE Date of last revision: 22 August 2017

6. How the atmosphere gets saturated
Convective development
Orographic ascent
Document Reference: RTC-PRE Date of last revision: 22 August 2017

7. How the atmosphere gets saturated
Convective development
Orographic ascent
Frontal uplift
Document Reference: RTC-PRE Date of last revision: 22 August 2017

8. How the atmosphere gets saturated
Convective development
Orographic ascent
Frontal uplift
Mechanical turbulence
Document Reference: RTC-PRE Date of last revision: 22 August 2017

9. How the atmosphere gets saturated
Convective development
Orographic ascent
Frontal uplift
Mechanical turbulence
Slow widespread ascent
Document Reference: RTC-PRE Date of last revision: 22 August 2017

10. In Summary Convective development Orographic uplift Frontal uplift
Mechanical turbulence
Slow wide-spread ascent
Document Reference: RTC-PRE Date of last revision: 22 August 2017

11. How clouds are named
Cloud genera – height of the cloud base above the ground
Cloud specie – the shape of the cloud
– the internal structure of the cloud
Cloud variety – the macroscopic elements of the cloud
– the degree of transparency of the cloud
Supplementary cloud features
Accessory clouds
Document Reference: RTC-PRE Date of last revision: 22 August 2017

12. 10 Basic Cloud Genera Cirrus Cirrocumulus Cirrostratus Cumulonimbus
Low level
Middle level
High level
Cumulonimbus
15 km
Cirrus
Cirrocumulus
Cirrostratus
Altostratus
Nimbostratus
6 km
Altocumulus
Cumulus
Stratocumulus
2 km
Stratus
Document Reference: RTC-PRE Date of last revision: 22 August 2017

13. Convective cloud appearance Cumulus and Cumulonimbus
Heaps or piles of clouds formed as buoyant warm air rises by convection.
Cumulus and Cumulonimbus
Document Reference: RTC-PRE Date of last revision: 22 August 2017

14. Stratiform Cloud appearance
Widespread clouds either with rounded shapes or a smooth appearance.
Stratocumulus, Stratus, Altostratus, Altocumulus,
Document Reference: RTC-PRE Date of last revision: 22 August 2017

15. Cirriform cloud appearance
Fibrous or wispy clouds composed of ice crystals
Cirrus, Cirrostratus and Cirrocumulus
Document Reference: RTC-PRE Date of last revision: 22 August 2017

16. Thank you