1. MET 112 Global Climate Change -
CLOUDS and CLIMATE
Prof. Menglin Susan Jin
Department of Meteorology, San Jos State University
Outline
Clouds Formation
Clouds Climatology
Clouds and the Radiation Budget

6. A good repository of cloud photos in various categories can be found at

7. Clouds
by Christina Rossetti
White sheep, white sheep, On a blue hill, When the wind stops You all stand still When the wind blows You walk away slow. White sheep, white sheep, Where do you go?

8. A Scientist’s View of Clouds
Clouds are formed when air containing water vapor
is cooled below a critical temperature called
the dew point and the resulting moisture condenses
into droplets on microscopic dust particles
(condensation nuclei) in the atmosphere.
CLOUDS: A visible mass of liquid water droplets suspended
in the atmosphere above Earth's surface.

9. Video: cloud formation in Tucson
Timelapse of Tucson cloud formations
MET 112 Global Climate Change

10. Questions What role do clouds play on the Earth’s climate?
What would happen to our climate if clouds were to increase/decrease?
How does clouds formation change with pollution?
So today, after these very broad introductory comments, we will spend a short time looking at the nature of energy in the E-A system, then we will look at some very basic radiation concepts (here I don’t want to get bogged down in complex detail, I just want to give you an overview of basic radiation concepts). However it is important that you have a basic understanding, because radiation is the primary energy source for driving atmospheric and ocean circulation and for all life on earth.
Finally today, we’ll examine the mean annual global energy budget, concentrating especially on those significant climate leverage points.

11. MET 112 Global Climate Change
Video
DTS-5.mp4
Clouds-1.mp4 –clouds and aerosols
MET 112 Global Climate Change

12. Clouds Roles - Importance of Clouds
Clouds is part of hydrological cycle to move water
Clouds is key in energy
Clouds absorb/reflect short wave radiation
(clouds alebedo effect)
Clouds emit longwave radiation back to space
clouds absorb surface longwave radiation and keep the heat in the atmosphere to warm the surface
(clouds greenhouse effect)
MET 112 Global Climate Change

13. 100% of the incoming energy from the sun is balanced by
100% percent total energy outgoing from the earth.
incoming energy from the Sun = outgoing energy from the Earth. 13

14. MET 112 Global Climate Change
since the Earth is much cooler than the Sun, its radiating energy is much weaker
(long wavelength) infrared energy. energy radiation into the atmosphere as heat,
rising from a hot road, creating shimmers on hot sunny days.
The earth-atmosphere energy balance is achieved as the energy received from the Sun
balances the energy lost by the Earth back into space.
So, the Earth maintains a stable average temperature and therefore a stable climate.
MET 112 Global Climate Change 14

15. Earth System Water Cycle15

16. Clouds can form along warm and cold fronts, where air flows up
the side of the mountain and cools
as it rises higher into the atmosphere,
and when warm air blows over a colder surface,
such as a cool body of water.

17. Water in the atmosphere
Definitions:
Evaporation:
Condensation:
Precipitation:

18. Water in the atmosphere
Definitions:
Evaporation:
Condensation:
Precipitation:
Process where a liquid changes into a gas
Process where a gas changes into a liquid
Any liquid or solid water that falls from the atmosphere to the ground. (i.e. RAIN!)

19. Condensation
The process by which water vapor changes to a cloud droplet
Water vapor molecules may ‘stick’ to condensation nuclei and grow (billions) to eventually form cloud droplet.
Examples of condensation nuclei include:
Dust
Salt
Smoke
Condensation occurs primarily as temperature cools:
colder the molecules more likely they are to ‘stick’ to
other molecules

21. Aerosols Affect Cloud Droplet Size
1.Aerosols serve as cloud condensation nuclie (CCN)
Ocean case
Land case
CCN
CCN
2. More aerosols, they will compete for water vapor to condense on, so smaller cloud droplet
MET 112 Global Climate Change

22. Why ocean has larger cloud droplets than land?
Zonal Mean Cloud Effective Radius (M. D. King, S. Platnick et al. – NASA GSFC)
Why ocean has larger cloud droplets than land?
July 2006 (Collection 5)
Aqua

23. Clouds and radiation Cloud - Climate Interactions
Albedo effect - COOLING
Clouds reflect incoming solar radiation.
The cloud droplet size and total water content determine the overall reflectivity.
Greenhouse effect - WARMING
Clouds are good absorbers (and emitters) of long wave (infrared) radiation.

24. Clouds and day to day temperatures
Imagine that you are going camping in the Sierras with your friends. On the first day (and evening) it is clear, while on the second day (and evening) it is cloud. Based on this information alone:
Which day would be warmer?
Which evening would be warmer?
Explain your answers.

25. Which day would be warmer?
First day (clear)
Second day (cloudy)
Both the same

26. Which evening would be warmer?
First day (clear)
Second day (cloudy)
Both the same

27. Clouds types

28. Low and High clouds Consider two types of clouds: Low levels clouds
High levels clouds
Q: How is the Earth’s surface energy budget different for low clouds compared to high clouds?

29. Clouds and Climate Cloud A: Low level, (dark, thick)
Cloud B: High level, light
(sub visible or thin)

30. Clouds and climate Cloud A: Low level, (dark, thick)
Cloud B: High level, light
(sub visible or thin)
Excellent reflector of incoming radiation; good absorber/emitter of infrared radiation
Fair/poor reflector of incoming radiation; good/excellent absorber/emitter of infrared radiation
So, clouds both warm and cool the earth.
Overall, though, clouds act to cool the earth

31. Changes in clouds Increases in low level clouds will:
Increases in high level clouds will:

32. Changes in clouds Increases in low level clouds will:
cool the surface (cooling outweighs warming)
Increases in high level clouds will:
warm the surface (warming outweighs cooling)

33. Cirrus

34. Altocumulus (possibly cirrocumulus, depending on altitude of the clouds)

35. Stratocumulus

36. Broken stratocumulus

37. Nimbostratus

38. Cumulus humilis (commonly called 'fair weather cumulus')

39. Cumulus

40. Cumulus

41. Cumulus

42. Cumulus

43. Cumulonimbus

44. Stratus

45. Stratus

46. Cirrus

48. Clouds That Look Like Things

49. Explain how the earth’s climate would change as a result of aircraft contrails.

50. Class Participation
Concept Map

51. Activity : Water Concept Map
Draw a concept map using the following terms. You may add additional terms if you wish.
Water vapor
Ice
Liquid water
Condensation
Evaporation
Gas
High Cloud
Low Cloud
Precipitation
Condensation nuclei
Temperature
Warming
Cooling
Air