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Prof. Steve AckermanUniversity of Wisconsin
2009 Teaching Excellence AwardAmerican Meteorological Society
Textbook:Meteorology
Understanding the Atmosphere2nd Edition
Ackerman & Knox
your topics of interest in ATSC 2000
topic score
Chapter 11) thunderstorms and tornadoes 53
Chapter 15) human influences on climate 29
Chapter 6) atmospheric forces and wind 19
Chapter 7) global-scale winds 17
Chapter 8) hurricanes & El Nino 16
Chapter 2) the energy cycle 13
Chapter 9) air masses and fronts 13
Chapter 3) temperature 8
Chapter 4) water in the atmosphere 8
Chapter 10) extra-tropical cyclones and anticyclones 8
Chapter 5) observing the atmosphere 7
Chapter 13) past & current climate 5
topics I propose we cover in this course
topic score
Chapter 11) thunderstorms and tornadoes 53
Chapter 15) human influences on climate 29
Chapter 6) atmospheric forces and wind 19
Chapter 7) global-scale winds 17
Chapter 8) hurricanes & El Nino 16
Chapter 2) the energy cycle 13
Chapter 9) air masses and fronts 13
Chapter 3) temperature 8
Chapter 4) water in the atmosphere 8
Chapter 10) extra-tropical cyclones and anticyclones 8
Chapter 5) observing the atmosphere 7
Chapter 13) past & current climate 5
and of course Chapter 1) Introduction
chapter 1: Introduction
1.1 Weather vs climate1.2 Atmospheric composition
– Focus on greenhouse gases
1.3 Atmospheric structure– Focus on the ozone hole
History of meteorology
• Babylonians, Chinese: astrometeorology• Aristotle: “meteorologia”• 16th-17th century: instruments and
scientific method (Descartes)– barometer (Torricelli, 1643, mercury)– thermometer (Galileo, 1592, Fahrenheit,
1714)• 1843: real-time data via telegraph• 1920’s: polar front theory (Bergen school)• 1940’s: upper-air observations
(radiosondes)• 1950’s: radar• 1960’s: first satellites and NWP models
weather …
our own weather servermore weather links
Chapter 1.1: weather vs. climate
Hurricane Katrina8/28/05 17 UTC
precipitation topography
EuropeNorth America
January mean temperature
Boston
London
Off Labrador in March Scotland in March
Define weather and climate…
Your turn!
• Weather:– A depiction of the state of the atmosphere at one
point in time.
• Climate:– A depiction of the ‘typical’ weather, based on
observations taken over a period of time.
Which one is a statement about weather, which one about
climate?
• Yesterday’s high in Laramie was 69°F
• That’s 4 degrees below the average high for this time of the year.
Click here for the current Laramie weather forecast
weather or climate ?
from 3-monthly to daily precip
weather or climate ?
image source
What is an ‘anomaly’?
• A departure from ‘normal’.– Especially climate data are often shown as anomalies, e.g.
a drought.
For how many days can we predict the weather?
10 days
Why?
The atmosphere, like any other fluid, behaves chaotically
Edward Lorenz, 1963: Deterministic nonperiodic flow. Journal of Atmospheric Sciences. Vol.20 : 130—141.Edward Lorenz in Wikipedia
“climate” is not constant!
last 150,000 years last 1,000 years
instrument record: last 125 years
regional variations in long-term change: global
regional variations in long-term change: USA
US temperature trend 1941-2005
long-term change in Wyoming
• We know that weather becomes unpredictable after ~10 days • So how can the CPC produce a seasonal outlook for the drought?
• Climate anomalies tend to persist for some time, months to seasons. • Why ?
Can we predict climate fluctuations?
El Niño: a change in
SST, winds, and rainfall in the equatorial
Pacific
El Niño has global impacts...
El Niño has some effect on precipitation in the US.
Why?
winter precipitation anomaly
anomaloussea surface temperature
1998 El Niño: SST & jet stream
jet stream
Coupled atmosphere-ocean models predict the SST out to about a year.
An El Niño is predicted for next winter …
source
• That does not mean that long-term climate change is even less certain.
• We cannot predict that July 2035 will be an ‘unusually’ warm month compared to what is typical then, but we are confident that that the 2030s will be warmer than the current decade.
• This is based on climate model predictions that take into account changes in greenhouse gases, earth surface conditions, and clouds.
Conclusion: there is some limited guidance for the season ahead, but wrong predictions should not be a surprise.
Predicted global mean temperature change
between 2000 and 2100
for 5 different CO2 emission scenarios.
source
Both study the atmosphere
Key atmospheric observations
Chapter 1.2: atmospheric composition
360 ppm
Recent trend in atmospheric CO2
Recent trend in atmospheric CO2
The long-term rise in CO2 levels parallels fossil fuel use.
the global carbon cycle
A visit from Mars …
Pop quiz
• The Earth’s atmosphere consists mostly of: – a: carbon dioxide; – b: oxygen; – c: water vapor; – d: nitrogen.
Discussion: our atmosphere is key to the habitability of the Earth. Are we alone in that regard, or do other planets have an atmosphere as well ?
feature Mars Earth Venusmean distance from the Sun (millions of km)
228 150 108
mean surface temperature C -50 12 460main gas in atmosphere 95% CO2 78% N2 97% CO2
surface pressure hPa 6 1,013 90,000
gravitational acceleration m/s2 3.8 9.8 8.8
Mars Earth Venus
Pop quiz
• Compared to the Earth, both Mars and Venus: – a: are warmer; – b: have a higher surface pressure; – c: are closer to the Sun;
– d: have relatively more CO2 in their atmosphere.
Chapter 1.3: Vertical structure of the atmosphere
radiosonde balloon
satellites
real-time soundings plotted
altitude: km
altitude: 1000 ft
temperature: °C
temperature: °F
pressure: hPa
0 0 15 59 10131 3 9 48 9002 6.5 2 36 795
2.22 7.3 1 34 7783 10 -5 23 7004 13 -11 12 6165 16 -18 0 5309 29 -44 -47 30715 49 -83 -117 120
ICAO standard atmosphere
Pop quiz
• The lowest two layers of the atmosphere are: – a: thermosphere, stratosphere; – b: troposphere, ionosphere; – c: mesosphere, stratosphere;– d: troposphere, stratosphere.
magnetosphere
Aurora Australis, May ’91Space Shuttle Discovery
O3
“Good” vs. “Bad” Ozone
• “Good”: Stratospheric ozone, which screens out much of the incident UV radiation from the sun.
• “Bad”: Tropospheric ozone, an anthropo-genic air pollutant , damages health and the environment.
Chapman cycletextbook, p. 446-449
• O2 +h 2O (<0.25 m - UV-c)
• O + O2 + M O3 + M
• O3 +h O + O2 (<0.31 m - UV-b)
• O + O3 2 O2
Formation:
Destruction:
CFC gases destroy the “good” ozone
Montreal protocol (1987): complete phase-out of CFC production
UV radiation penetrating to the Earth surface
UV-aUV-b
4.8"
UV-c(skin cancer, eye cataracts ...)
Lara
mie
(2.
2 km
)
MO3
Surface observations
Surface observations
temperature (°F)
dewpoint (°F)
weather
sea level pressure (mb)
wind direction and speed
cloudiness
visibility (miles)5
learning applet
Weather symbols
Cloud cover
If reported value greater than 500: Initial 9 is missing. Place it on left, then divide by 10. For example: 827 becomes 982.7 mb.
If reported value less than 500: Initial 10 is missing. Place it on left, then divide by 10. For example: 027 becomes 1002.7 mb.
Sea level pressure
wind
1 Knot = 1.15 MPH
direction
speed
current surface observations
summary
• Chapter 1, intro to the atmosphere– weather vs climate– vertical structure of the atmosphere– atmospheric gas composition
• Chapter 15, human influence on climate– climate change (p. 441-443 and p. 453-464)
- to be revisited