Lecture 2 Atmospheric Constituents - PowerPoint Presentation

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Lecture 2

Atmospheric Constituents

and Vertical Structure

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Learning Goals for Chapter 1

Having an understanding of the main

COMPONENTS of the atmosphere and how they have changed over time. Understand how and why atmospheric PRESSURE changes with height.Understand how and why atmospheric TEMPERATURE changes with height

http://

en.wikipedia.org/wiki/Halemaumau_Crater#mediaviewer/File:Rainbow_and_sulfur_dioxide_emissions_from_the_Halema%60uma%60u_vent.jpg

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

http://www.nc-climate.ncsu.edu/edu/k12/.AtmStructure

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Chapter 1 – Introduction to the Atmosphere

Weather

The state of the atmosphere at any given time.ClimateA description of aggregate weather conditions.The sum of all statistical weather information that helps describe a place or region.

“Climate is what you expect, but weather is what you get”

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The Atmosphere

VERY THIN99% is within 19 miles (30 km) of the surface.Provides the air we breathProvides protection from damaging UV radiation from the Sun

NOT TO SCALE!!!!

The Layers of the Atmosphere

http://en.wikipedia.org/wiki/File:AtmosphericLayers.jpg

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Modern Atmospheric Composition

78% Nitrogen (

N2)21% Oxygen (O2) 1% Argon (Ar) Other Gases and ConstituentsCarbon Dioxide (CO2) – from respiration, combustion, GHGMethane (CH4) – cows, wetlands, rice patties, low oxygen environments, GHGOzone (O3) – in both the stratosphere (good) and troposphere (bad)Water (H2O) – 0-5% variable over the surface of the earthHydrogen (H2)Helium (He)Carbon Monoxide (CO)Ammonia (NH3)Nitrogen Oxide (NO)Nitrous Oxide (N2O)Sulfur Dioxide (SO2)Nitrogen Dioxide (NO2)Particles – Aerosols, dust, smoke

http://commons.wikimedia.org/wiki/File:Air_composition_pie_chart.JPG

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Atmospheric Composition

Where did all the Nitrogen come from

?

Nitrogen Cycle

The answer lies mostly in

three facts: nitrogen is volatile in most of its forms it is unreactive with materials that make up the solid earth it is very stable in the presence of solar radiation.

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Atmospheric Composition

Where did all the Nitrogen come from

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Nitrogen Cycle

Over geological time, it has

built up

in the atmosphere to a much greater extent than oxygenIt is an important component of life on earth (Nitrogen Cycle)

http://commons.wikimedia.org/wiki/File:Nitrogen_Cycle.svg

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Atmospheric Composition

The

primary way in which the Earth generates oxygen is through photosynthesis.Photosynthesis accounts for 98% of the world's atmospheric oxygenThe breakup of water molecules by ultraviolet radiation composes the other 1-2%.

http://commons.wikimedia.org/wiki/File:Photosynthesis.gif

Where does the oxygen come from?

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Atmospheric Composition

Why is Argon Third?

Argon is formed by radioactive decayReleased slowly into the atmosphere through volcanic activity. It is an inert (and nonradioactive) gas and does not react chemically, so it gradually accumulates in the atmosphere. Fun Fact: Used in “Neon” Lights! Argon is the gas used for lilac/purple colors.

http://en.wikipedia.org/wiki/Volcanic_gas#mediaviewer/File:MSH04_crater_eruption_image_1213PDT_10-01-04.jpg

https://en.wikipedia.org/wiki/Argon

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Atmospheric Composition

Carbon dioxide

News worthy  Global Climate ChangeCO2 is an efficient absorber of energy emitted by the sun!Present in tiny amounts ~0.04% or ~409.99 ppmAs of Jan 3rd, 2019!

http://commons.wikimedia.org/wiki/File:Smokestacks_3958.jpg

http://en.wikipedia.org/wiki/Portal:Global_warming

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Atmospheric Composition

Carbon

dioxideAmount of CO2 is relatively constant over the earthRecords a steady increase since the 1960s….Keeling Curve  We’ll talk more about later These measurements made in HAWAII on top of Mauna Loa

http://en.wikipedia.org/wiki/Charles_David_Keeling#mediaviewer/File:Mauna_Loa_Carbon_Dioxide.png

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Atmospheric Composition

Variable Components

Water VaporVaries from 0-4% by volumeClouds and precipitationHeats the atmosphere like CO2Releases or absorbs energy when it changes states (gas-liquid-solid)AerosolsTiny solid and liquid particlesDust, pollution, sea salt, ash, smoke, biogenic particlesOzoneNEXT SLIDE!

http://en.wikipedia.org/wiki/Sirocco#mediaviewer/File:Sirocco_from_Libya.jpg

http://en.wikipedia.org/wiki/Great_Smoky_Mountains#mediaviewer/File:Clifftops4-7-07.jpg

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Atmospheric Composition

Ozone (O

3)Three Oxygen Molecules!Concentrated high above the surface (in the stratosphere)Protects us from UV rays from the sun (what gives us sun burns)

http://commons.wikimedia.org/wiki/File:Hole_in_the_Ozone_Layer_Over_Antarctica_-_GPN-2002-000117.jpg

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Atmospheric Composition

Ozone Hole

We’ll go into detail later…Predominantly found in the Antarctic, though one happened in the Arctic in 2011.Montreal Protocol – What happens when the scientists and politicians of the world come together. SUCCESS!!!

http://commons.wikimedia.org/wiki/File:Hole_in_the_Ozone_Layer_Over_Antarctica_-_GPN-2002-000117.jpg

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Evolution of the Atmosphere

http://en.wikipedia.org/wiki/Hadean#mediaviewer/File:Volcano_q.jpg

First atmosphere:

Hydrogen (H) and Helium (He) 4.6 billion years agoSwept away by solar winds, escaping the earth’s hot surface.Primeval Phase:An atmosphere unfamiliar to us, next few slidesModern Phase:What we live in now

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Primeval Atmosphere

http://en.wikipedia.org/wiki/Hadean#mediaviewer/File:Earearth.png

The principle source of atmospheric gases was

OUTGASSINGThe release of gases from rock through volcanic eruptions and impact of meteorites

Primeval Atmosphere was mostlyCO2, N2, H2O, little CH4, NH3 (ammonia), SO2, HCl.Radioactive decay of an isotope of potassium added argon.Free Oxygen (O or O2) was absent!!!

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Primeval Atmosphere

After 4 billion years, the Earth’s surface cooled

Water vapor to condense into clouds and rain

Oceans and rivers formed

CO

2 dissolves in waterrain, and oceans, “washed out” some of the CO2… cooling the planet further.After life emerged, primarily photosynthetic bacteria emergedO2 began building up

http://en.wikipedia.org/wiki/Hadean#mediaviewer/File:Earearth.png

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Extent of the Atmosphere

No clear boundary

at the upper atmosphereRapidly thins as altitude increases (density decreases)Half the atmosphere lies below ~5.6 km (3.5 miles)Pressure decreases with Height.Rate of pressure decrease is not constant (red line)Air is HIGHLY compressible

MEMORIZE this PLOT!

http://www.nc-climate.ncsu.edu/edu/k12/.AtmStructure

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Extent of the Atmosphere

Standard Atmospheric Pressure:

1013.25 mb1013.25 hPa29.92 in. Hg.Near surface air is more dense.Decreases rapidly at first then more slowly

MEMORIZE this PLOT!

http://www.nc-climate.ncsu.edu/edu/k12/.AtmStructure

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Thermal Structure of the Atmosphere

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

Four Layers:

Troposphere

Stratosphere

Mesosphere

Thermosphere

Three Transition Layers

Tropopause

Stratopause

Mesopause

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Troposphere

Warmed by the surface of the Earth!!!!

Where “Weather” happens

Due to vertical and horizontal mixing of airTemperature DECREASES with heightEnvironmental lapse rate6.5 deg K per km3.6 deg F per 100 ftHighly variableDecreases until ~12 kmTROPOPAUSE!

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

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Stratosphere

Temperature

INCREASES with heightDue to the presence of OZONE, which heats the layerOzone absorbs solar radiationMaximum from 15-30 kmWe study this layer withWeather balloonsHigh altitude aircraftSatellites

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

http://en.wikipedia.org/wiki/Mount_Pinatubo

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Mesosphere

COLDEST

temperatures in the atmosphere are observed here

Not heated by the Earth or Ozone!

Pressure is very lowIs the least studied region

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

http://en.wikipedia.org/wiki/Polar_stratospheric_cloud

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Thermosphere

Begins after the Mesosphere and has no well defined upper limit

Temperature begins to

INCREASE with height again!Temperature is defined as:Average speed at which molecules moveGases here move FAST in thermosphereEven though there are few of them…What if an astronaut exposed his hand?It would not feel hot, not enough particles!

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg

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Ionosphere

Located between 80-400 km

Overlaps with the ThermosphereIs an electrically charged layerImportant for long wave radio transmission

No influence on daily weather

The ionosphere is also the site of

aurora

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Auroras

Aurora borealis

(northern lights)Aurora australis (southern lights)Closely correlated with solar-flaresGeographic location is important(Earth’s magnetic poles)Appear in the night sky as overlapping curtains Bottom at 100 km (62 miles)Tops at 400 km (248 miles or higher)

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Auroras

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Aurora Borealis

from the surface (Norway)

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Aurora Borealis from the

International Space Station

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Key Information 1

Know the main components of the atmosphere, their percentages and how they reached current levels

N2 (78%), O2 (21%), Argon (1%)Identify other components of interest:CO2, Ozone, Water Vapor, Particles, etc.Describe the primeval atmosphere and how the current atmosphere evolvedIdentify processes involved (i.e. Outgassing and Photosynthesis)

http://commons.wikimedia.org/wiki/File:Air_composition_pie_chart.JPG

http://en.wikipedia.org/wiki/Halemaumau_Crater#mediaviewer/File:Rainbow_and_sulfur_dioxide_emissions_from_the_Halema%60uma%60u_vent.jpg

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Key Information 2

Be able to draw how atmospheric pressure changes with height.

Know

altitudes & pressure valuesKnow at what altitude below which 50% of the atmosphere is located5.5 kmKnow why the pressure and density curves look the way they do:Gravity & Compressibility of airKnow Standard Pressure Values1013.25 mb29.92 in. Hg

http://www.nc-climate.ncsu.edu/edu/k12/.AtmStructure

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Key Information 3

Be able to draw how atmospheric Temperature changes with height!

Know

altitudes and temperature valuesIdentify each of the layers and their boundariesTroposphere, tropopause, stratosphere, stratopause, mesosphere, mesopause, thermospehre & ionosphereBe able to describe how and why temperature changes in each layer.Know what an aurora is and why they happen.

http://commons.wikimedia.org/wiki/File:Atmprofile.jpg