Prof. Steve Ackerman University of Wisconsin 2009 Teaching Excellence Award American Meteorological Society Textbook: Meteorology Understanding the Atmosphere.

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