Vehicles of the Gods or the result of the coalescence of billions of water droplets? Of course today we know the answer. This presentation will will explore what we used to believe, how we came to know what we know now, and what current theory predicts about the future. From the Un-Distinguished Lecture Series (http://ws.cs.ubc.ca/~udls/). The talk was given May 25, 2007.

1. Clouds
Presented by Sancho McCann

2. QuickTime and a
decompressor
are needed to see this picture.

3. Home of the Gods
• Mount Olympus
• Protected by a great
gate of clouds

4. Powers of clouds
• Herakles lifted by a
cloud
• Nephele, a Nypmh
was formed from a
cloud

5. Christian Writings
• The Transfiguration
of Jesus

7. Why?
Photo by http://www.flickr.com/people/mutephotoblog/

8. Aristotle
• Meteorologica c.
350 B.C.
Photo by Eric Gaba

9. Meteorology (Aristotle)

10. Meteorology since Aristotle
Pascal finds
Torilcelli invents pressure
decreases with Halley
barometer characterizes
height
this decrease
Gelileo invents
thermometer
Meteorology
1648
350 B.C. 1606 1643 1686

11. Meteorology since Aristotle
Fahrenheit
establishes a
measurement Celsius
Synoptic
scale based on a proposed the
weather
mercury Centigrade
forecasting
thermometer scale
1742 1860
1714

12. Meteorology since Aristotle
First proposed link von Neumann
between CO2 and assembled a team to
First attempt at
global warming apply the
numerical
computation of the
weather First ENIAC to weather
prediction radiosonde forecasting
1930
1922 1950
1938

13. Clouds Today
• 3 Ingredients
• Some Types
• Effects on our future

14. Ingredients
Condensation Nuclei
Moisture
Cooling
Photos by http://www.flickr.com/people/cobalt/
http://www.flickr.com/people/aricee/
http://www.flickr.com/people/560506/

15. Cooling: Orographic lifting
Photo by http://www.flickr.com/people/serac/

16. Cooling: Convective lifting
QuickTime and a
decompressor
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17. Cooling: Advection cooling
QuickTime and a
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18. Two Categories of Clouds
• Cumulus
– Vertical build­up
• Stratus
– Horizontal layers
Photos by http://www.flickr.com/people/teo/
and http://www.flickr.com/people/b16/

19. Types of Clouds
• Cirrus
– Highest clouds
– Wispy
– Thin sheets
– Made of ice crystals
– Cirrostratus
– Cirrocumulus
Photo by http://www.flickr.com/people/teodegas/

20. Types of Clouds
• Mid­level clouds
– Motion apparent
– More substantial
than cirrus
– Altostratus
– Altocumulus
Photo by http://www.flickr.com/people/nicholas_t/

21. Types of Clouds
• Cumulonimbus
– Extreme
vertical
development
– Thunderstorms
– Hail
Photo by http://www.flickr.com/people/pulpolux/

22. Effect on the Future
• How will cloud cover be affected by global
warming?
• How will global warming affect cloud cover?

23. Effect of Clouds

24. Effect of Clouds
• Contrails alone might account for half a
degree increase in temperature since 1975
Photo by http://www.flickr.com/photos/good_day/

25. Effect of Global Warming
• Effect of global warming on cloud coverage is
unknown
• Difficulty in modeling such small scale events
like cloud formation
Photo by http://www.flickr.com/photos/quiero­un­pantano/

26. Computers and Clouds
QuickTime and a
YUV420 codec decompressor
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From the Pittsburgh Supercomputing Center

27. Computers and Clouds
QuickTime and a
YUV420 codec decompressor
are needed to see this picture.
SIGGRAPH 2005

28. Additional Resources
• Aristotle. Meteorology. http://classics.mit.edu/Aristotle/meteorology.html
• NASA. The Importance of Understanding Clouds. 2005.
http://eospso.gsfc.nasa.gov/ftp_docs/NASA­Facts­UnderstandingClouds.pdf
• Steve Graham, Claire Parkinson, and Mous Chahine. Weather Forecasting Through the
Ages. http://earthobservatory.nasa.gov/Library/WxForecasting/printall.php
• MIT OpenCourseWare: Earth, Atmospheric, and Planetary Sciences.
http://ocw.mit.edu/OcwWeb/Earth­­Atmospheric­­and­Planetary­Sciences/index.htm
• Richard Hamblyn. The Invention of Clouds: How an Amateur Meteorologist Forged the
Language of the Skies. 2001.