Transcript Document

Lecture 1-Nats 101
http://www.ncdc.noaa.gov/oa/climate/research/2005/ann/ann05.html
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Lecture 1-Nats 101
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Local Weather and Climate:
The North American Monsoon
• Tucson gets half of its rainfall during the summer
• Sonora, Mexico gets most of its rainfall during the
summer
• During summer, high pressure sets up to the
east/northeast of Arizona which brings moisture in
from the south
• The monsoon is still going: Thunderstorms yesterday
• For a monsoon overview and daily forecast, see:
http://www.wrh.noaa.gov/twc/monsoon/monsoon.php
http://www.atmo.arizona.edu/products/models/forecasts/forecast.html
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Local: Recent Monsoon Rainfall
• Record water flow
through the Sabino
and Rillito Creeks
on July 31
• Rillito flow higher
than Colorado river!
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See http://fpnew.ccit.arizona.edu/kkh/rillito.flood.jul.06.htm
Course Building Blocks
Intro  1st week or so
Energy  ~2 weeks
Moisture  ~2 weeks
Dynamics  ~3 weeks
Above are interdependent
• Specific Topics  ~6 weeks
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Atmospheric Composition
Permanent Gases
Ahrens, Table 1.1, 4th Ed.
• N2 and O2 are most
abundant gases
• Percentages hold
constant up to 80 km
• Ar, Ne, He, and Xe
are chemically inert
• N2 and O2 are
chemically active,
removed & returned
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N2 and O2
N2
Boiling point: 77 °K or -196°C or –320 °F
O2
Boiling point: 90 °K or -183 °C or -297 °F
Balance between input (production) and output (destruction):
Input:plant/animal decaying
Input:plant photosynthesis
Output: soil bacteria;
Output: organic matter decay
oceanic plankton-->nutrients
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chemical combination (oxidation)
breathing
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Atmospheric Composition
Important Trace Gases
Ahrens, Table 1.1, 3rd ed.
Which of these is now wrong
even
Lecture
1-Natsin
101the 4th edition of Ahrens?
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Carbon Dioxide CO
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Sources
vegetative decay
volcanic eruptions
animal exhalation
combustion of fossil fuels
(CH4 + 2 O2 > 2 H2O + CO2)
Sinks
photosynthesis (oxygen production)
dissolves in water
phytoplankton absorption (limestone formation)
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CO2 Trend
“Keeling Curve”
Some gases vary by season and
over many years.
The CO2 trend is the cause for
concern about global warming.
CO2 increases
in northern spring,
decreases in northern fall
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See http://earthguide.ucsd.edu/globalchange/keeling_curve/01.html
H2O Vapor Variability
Precipitable Water (mm)
Some gases can vary
spatially and daily
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Aerosols
1 cm3 of air can contain as many as 200,000
non-gaseous particles.
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dust
dirt (soil)
ocean spray
volcanic ash
water
pollen
pollutants
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Aerosols - Volcanic Ash
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Fig. 1-4, p.6
Aerosols - Dust Particles
Dust Storm on Interstate 10, between Phoenix and Tucson, AZ.
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Aerosols
• Provide condensation nuclei for water
vapor.
• Provide a surface area or catalyst needed for
much atmospheric chemistry.
• Aerosols can deplete stratospheric ozone.
They can also cool the planet by reflecting
sunlight back to space.
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Reading Assignment
• Ahrens
Pages 1-22; 425-426-427 (Appendix A:
Units etc.), 431-432 (Appendix C:
Weather chart symbols)
Problems 1.2, 1.3, 1.10, 1.14, 1.17, 1.18,
1.20
(1.17  Chapter 1, Question 17)
Don’t Forget the 4”x6” Index Cards
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