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Textbook: Meteorology Understanding the Atmosphere 2nd Edition Ackerman & Knox Prof. Steve Ackerman University of Wisconsin 2009 Teaching Excellence Award American Meteorological Society 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 climate 1.2 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 Chapter 1.1: weather vs. climate weather … our own weather server more weather links Hurricane Katrina 8/28/05 17 UTC precipitation topography January mean temperature North America Europe London Boston 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 Can we predict climate fluctuations? • 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 ? 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. winter precipitation anomaly Why? 1998 El Niño: SST & jet stream anomalous sea surface temperature jet stream Coupled atmosphere-ocean models predict the SST out to about a year. An El Niño is predicted for next winter … source Conclusion: there is some limited guidance for the season ahead, but wrong predictions should not be a surprise. • 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. 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 mean distance from the Sun (millions of km) mean surface temperature C main gas in atmosphere surface pressure hPa gravitational acceleration m/s Mars 2 Mars 228 Earth 150 Venus 108 -50 95% CO2 6 3.8 12 78% N2 1,013 9.8 460 97% CO2 90,000 8.8 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 ICAO standard atmosphere altitude: km 0 1 2 2.22 3 4 5 9 15 altitude: temperature: temperature: pressure: 1000 ft °C °F hPa 0 15 59 1013 3 9 48 900 6.5 2 36 795 7.3 1 34 778 10 -5 23 700 13 -11 12 616 16 -18 0 530 29 -44 -47 307 49 -83 -117 120 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 ’91 Space 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 anthropogenic air pollutant , damages health and the environment. Chapman cycle textbook, p. 446-449 Formation: • O2 +hn 2O (l<0.25 mm - UV-c) • O + O 2 + M O3 + M Destruction: • O3 +hn O + O2 • O + O3 2 O2 (l<0.31 mm - UV-b) CFC gases destroy the “good” ozone Montreal protocol (1987): complete phase-out of CFC production UV radiation penetrating to the Earth surface 4 .8 " UV-c UV-b (skin cancer, eye cataracts ...) UV-a M O3 Surface observations Surface observations temperature (°F) sea level pressure (mb) weather 5 wind direction and speed visibility (miles) dewpoint (°F) cloudiness learning applet Weather symbols Cloud cover Sea level pressure 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. 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 - to be revisited (p. 441-443 and p. 453-464)