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Chapter 1: The Chapter 1: The Earth’s Earth’s

AtmosphereAtmosphere Overview of the Earth’s atmosphereOverview of the Earth’s atmosphere Vertical structure of the Vertical structure of the

atmosphereatmosphere Weather and climateWeather and climate

Q: You can live for a few minutes only: a) without air b) without water c) without food

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Overview of the Overview of the Earth’s Earth’s

AtmosphereAtmosphere• when the earth is scaled to the size of an apple, 99% of atmosphere is no thicker than the skin on an apple

• Water vapor molecules are invisible: clouds;

sink: condensation/deposition source: evaporation/sublimation/ transpiration (through vegetation roots)

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Composition of the Composition of the AtmosphereAtmosphere

permanent gasespermanent gases

• NitrogenNitrogen source: decaying of plant and animal matter source: decaying of plant and animal matter sink: soil bacteria; sink: soil bacteria; ocean planktonocean plankton

• OxygenOxygen source: plant photosynthesis (sun + COsource: plant photosynthesis (sun + CO22 + H + H22OO lead to sugar and Olead to sugar and O22)) sink: organic matter decaysink: organic matter decay breathing (take in Obreathing (take in O22, release CO, release CO22))Q: which one is larger between the production and destructionQ: which one is larger between the production and destruction rates: a) production; b) destruction; c) equal rates: a) production; b) destruction; c) equal 4

380 ppm = 380/106 = 380 * 10-4/102 = 0.038%

Q: which is the most important greenhouse gas in the atmosphere? a) carbon dioxide; b) water vapor; c) methane, d) ozone

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Composition of the Composition of the AtmosphereAtmosphere

Carbon dioxide and the greenhouse Carbon dioxide and the greenhouse gasesgases

ozoneozone aerosolsaerosols pollutants pollutants

• Ozone at high altitudes Ozone at high altitudes (stratosphere) is “good”;(stratosphere) is “good”;

ozone at low altitudes ozone at low altitudes (troposphere) is “bad.”(troposphere) is “bad.”

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Q: List threeQ: List three

sources and sources and twotwo

sinks of COsinks of CO22 in in

the the atmosphereatmosphere

Q: why is the Q: why is the global COglobal CO22 concentration concentration is lower in is lower in summer than in summer than in winter?winter?

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The Early AtmosphereThe Early Atmosphere the first atmosphere: hydrogen, helium (most abundant the first atmosphere: hydrogen, helium (most abundant

gases found in the universe)gases found in the universe) the second atmosphere through outgassing from the the second atmosphere through outgassing from the

hot interior (via volcanoes and steam vents): hot interior (via volcanoes and steam vents): water water vapor, carbon dioxide, nitrogenvapor, carbon dioxide, nitrogen

evolution of the atmosphere: evolution of the atmosphere:

water vapor leads to oceans (via precipitation); water vapor leads to oceans (via precipitation);

carbon dioxide is dissolved in oceans; carbon dioxide is dissolved in oceans;

nitrogen is not active chemically; nitrogen is not active chemically;

water vapor is splitted (by energetic rays from the water vapor is splitted (by energetic rays from the sun)sun)

into oxygen and hydrogen (and hydrogen escapes)into oxygen and hydrogen (and hydrogen escapes)

• The evolution of life and the atmosphere are closely The evolution of life and the atmosphere are closely linked.linked. 8

Vertical Structure of Vertical Structure of the Earth’s the Earth’s AtmosphereAtmosphereRawinsonde is launched twice a day to

measure temperature, humidity, wind, and pressure of the lowest 30 km aboveSurface. It is called radiosonde if wind is not measured.

Q: where is the balloon launched in Tucson? a) airport; b) Mt. Lemmon, c) UA campus

Q: balloon is released at 00:00 UT (or GMT). What is the Tucson time? a) 5am, b) 3pm, c) 5pm

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A Brief Look at Air A Brief Look at Air Pressure and Air DensityPressure and Air Density

air density: air density: mass per unit volumemass per unit volume

air pressure: air pressure: air weight (mass times gravity) air weight (mass times gravity) above a levelabove a level

sea-level pressuresea-level pressure• Surface pressure: 1013 mb = 1013 hPa = 29.92 in.HgSurface pressure: 1013 mb = 1013 hPa = 29.92 in.Hg

Q: Baseballs travel farther in higher-altitude air (e.g., inQ: Baseballs travel farther in higher-altitude air (e.g., in Denver) than they do in lower-altitude air. This Denver) than they do in lower-altitude air. This statement is: a) true; b) false, c) undecided. statement is: a) true; b) false, c) undecided.

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Ps =14.7 psi =1013 hPa

Q: what is the typical tire pressure of your car? a) 1Ps; c) 2Ps; c) 3Ps

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Q: what is the percentage of O2 at the top of Mt. Everest relative to the sea level value? a) 13%

b) 23% c) 33% d) 43%

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Layers of the AtmosphereLayers of the Atmosphere vertical temperature vertical temperature

profileprofile TroposphereTroposphere lapse rate: 6.5lapse rate: 6.5ooC/1km;C/1km;

temperature inversiontemperature inversion

StratosphereStratosphere OO33 absorption absorption

mesospheremesosphere ThermosphereThermosphere OO22 absorption absorption

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The IonosphereThe Ionosphere electrified regions of the electrified regions of the

atmosphere: atmosphere: with large concentrations of with large concentrations of ions and free electrons. Ions are atoms and ions and free electrons. Ions are atoms and molecules that have lost or gained electrons.molecules that have lost or gained electrons.

D, E and F regionsD, E and F regions radio wavesradio waves

• When the radio was invented When the radio was invented by G. Marconi in the early by G. Marconi in the early 20th century, it was not 20th century, it was not known how radio waves known how radio waves traveled long distances traveled long distances through the atmosphere.through the atmosphere.

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AM radio travels farther at night than during the day 15

Weather and Weather and ClimateClimate

• Satellites• Radar• Radiosonde• Aircraft• Weather station

See ATMO web site

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Elements of WeatherElements of Weather

air temperatureair temperature air pressureair pressure humidityhumidity cloudsclouds precipitationprecipitation visibilityvisibility windwind

• Certain weather elements, likeCertain weather elements, likeclouds, visibility and wind, areclouds, visibility and wind, areof particular interest to pilots.of particular interest to pilots.

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ClimateClimate Statistics of weather, such asStatistics of weather, such as

mean values;mean values;

mean variations (e.g., seasonal mean variations (e.g., seasonal cycle);cycle);

extremesextremesQ: A city’s maximum temperature is 105oF. This information is related to: a) weather; b) climate; c) neither; d) either.Q: Today’s maximum temperature is 75oF. This information is related to: a) weather; b) climate; c) neither; d) either.

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A Satellite’s View of the A Satellite’s View of the WeatherWeather

geostationary satellitesgeostationary satellites• Atmospheric observation Atmospheric observation

from satellites is an from satellites is an important technological important technological development in development in meteorology. Othermeteorology. Otherimportant developments important developments include computers, internet, include computers, internet, and Doppler radar.and Doppler radar.

visible bandvisible band

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Storms of all SizesStorms of all Sizes

midlatitude cyclonic stormsmidlatitude cyclonic storms hurricanes and tropical stormshurricanes and tropical storms thunderstormsthunderstorms tornadoestornadoes

• Storms are very exciting, but they also play an Storms are very exciting, but they also play an important role in moving heat and moisture around important role in moving heat and moisture around throughout the atmosphere.throughout the atmosphere.

Q: based on prior slide, which system is larger?Q: based on prior slide, which system is larger? a) midlatitude cyclonic storm; b) hurricanea) midlatitude cyclonic storm; b) hurricane

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Doppler radar 22

A Look at a Weather MapA Look at a Weather Map

wind speed and directionwind speed and direction cyclones and anticyclonescyclones and anticyclones frontsfronts

• Wind direction is defined in the opposite way asWind direction is defined in the opposite way asocean currents: a southerly current means water is ocean currents: a southerly current means water is moving moving towardstowards the south. the south.

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Q: What is the wind direction in Chicago? a) southerly, b) northerly, c) easterly, d) westerly

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Weather and Climate in Weather and Climate in our Livesour Lives

wind chill, frostbite and hypothermiawind chill, frostbite and hypothermia heat exhaustion and heat strokeheat exhaustion and heat stroke cold spells, dry spells and heat cold spells, dry spells and heat

waveswaves severe thunderstorms and flash severe thunderstorms and flash

floodsfloods• The mathematical formula for determining the windThe mathematical formula for determining the wind

chill temperature has recently been revised due to newchill temperature has recently been revised due to newexperiments.experiments.

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Ice storm caused utility poles and power lines to be weighed down, forcing road closure. 27

Tucson, AZ

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