Intro to the Atmosphere• The layers of gas that surround the other

spheres of influence on our planet • Interacts frequently with

- Hydrosphere- Clouds,Humidity,Rain

- Lithosphere- Weathering,Wind Erosion,Dust Particles

- Exosphere- Blocks incoming Solar Radiation

- Biosphere- Us!, plants, animals

• Interacts frequently with- Hydrosphere- Clouds,Humidity,Rain

- Lithosphere- Weathering,Wind Erosion,Dust Particles

- ExosphereExosphere- Blocks incoming Solar Radiation

- Biosphere- Us!, plants, animals

• Measuring instruments- Thermometer- temperature

- Barometer- pressure

- Geiger Counter- radioactivity

- Chromatograph- chemical composition

• Space missions- satellites

- aircraft

• Theory- physics and chemistry

How do we know about the atmosphere?

Origins of Earth’s atmosphere

• Early on- volcanic activity isresponsible for atmospheric gases

- rich in CO2 (carbon dioxide)

- very different from today’s atmosphere

•

- increased the oxygen content in oceans then air

• Solar radiation also contributed- created other atoms by irradiating

existing components- ozone layer

simple plants and bacteria as planktonic life forms (phytoplankton) changed the atmospheric composition over 2 billion years

Composition (modern)Composition (modern)

NN22 (nitrogen) = 78 % (nitrogen) = 78 %

OO22 (oxygen ) = 21 % (oxygen ) = 21 %

Ar (argon) = 0.93 %Ar (argon) = 0.93 %

COCO22 (Carbon Dioxide) = 0.035% (Carbon Dioxide) = 0.035%

Aerosols and WaterAerosols and Water

• • dust and moisture particles smalldust and moisture particles smallenough to stay up in the atmosphereenough to stay up in the atmosphere

an inert gasan inert gas

a greenhouse gasa greenhouse gas

Clouds

formhere

The structure of

the atmosphere

• divided based on• the temperature

Composition is

unchanging here

Ozone Layer O3Ozone Layer O3

Ionosphere

Aurora Borealis & Australis

Ionosphere &

magnetosphere

AURORA BOREALIS movies

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Factors associated with the atmosphere

• Heat- different from temperature (avg. kinetic energy)

- usually measured as the temperature of the air

- F, C, K scales

- a function of the kinetic energy (molecular motion).

• Moisture- Measured as relative humidity

- a function of temperature and availability

- expressed as a percentage

• Pressure- Measured in millibars, pascals, or inches

Heat transferHeat transfer

One of the big things the atmosphere does!One of the big things the atmosphere does!

ConductionConduction

• • contact between air and groundcontact between air and ground

ConvectionConvection

• • mixing due to temp related density changesmixing due to temp related density changes

Radiation- also known as radiative or electromagnetic energyRadiation- also known as radiative or electromagnetic energy

• • absorbed and emitted by all objectsabsorbed and emitted by all objects

Heat transfer (2)Heat transfer (2)ConductionConduction

• • contact between hot & cool contact between hot & cool - - transfers E from hot to cooltransfers E from hot to cool

• • solids > liquids > gases solids > liquids > gases - - atmosphere poor atatmosphere poor at

conductionconduction

Convection (& Advection)Convection (& Advection)

• • "mixing" of hot & cold"mixing" of hot & cold- - Usually in currentsUsually in currents

- - Con- is vertical; Ad- is horizontal or lateralCon- is vertical; Ad- is horizontal or lateral

Radiation• Sun is the source of most radiation

- visible light = intermediate-wave radiation

- infrared (heat)= Longwave radiation

- X-rays, gamma rays, etc= very shortwave

• Earth also givesoff some radiation• Living things alsogive off radiation• Angle of approachand reflectiveproperties arecritical factors

Air PressureAir PressureThe "weight" of the air pressingThe "weight" of the air pressingdown on the Earth's surfacedown on the Earth's surface

• • measured by a Barometermeasured by a Barometer- - inches (or mm) of mercuryinches (or mm) of mercuryrising up in a tuberising up in a tube

• • adjusted according to heightadjusted according to heightabove avg. sea levelabove avg. sea level

- - less air pressing down from above at higherless air pressing down from above at higheraltitudesaltitudes

• • also takes into account motion of airalso takes into account motion of air- - sinking vs risingsinking vs rising

A simple barometer

Atmospheric Density

• • air is "thinner"air is "thinner" aloft- less atoms of italoft- less atoms of it

• • Pressure is Pressure is lower aloftlower aloft

• • Important forImportant for heatheat and and pressurepressure

transfer transfer

0 km

120 km

Surface isobar map with fronts

Moisture- the other main thing

• dependent on temperature- warmer = hold more water vapor

- colder = holds less water vapor

• results from - evaporation of liquid water

- cools surface and adds heat to air

- sublimation

- direct transformation from solid water(ice) to vapor

• Acts as a trap for longwave radiation (heat)

• Transports heat• Acts to transport water

Interaction of Radiation,Pressure,Moisture at macro, or global, scale

Interaction of Radiation,Pressure,Moisture at meso scaleInteraction of Radiation,Pressure,Moisture at meso scale

Weather patterns are dictated by moisture, pressure and temperature differences in various air masses

Weather patterns are dictated by moisture, pressure and temperature differences in various air masses• A hurricane (shown at right) is an extreme low pressure system that draws energy from warm water

• A hurricane (shown at right) is an extreme low pressure system that draws energy from warm water

Sea Breeze- Interaction of Radiation,Pressure,Moisture at micro scaleSea Breeze- Interaction of Radiation,Pressure,Moisture at micro scale

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