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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 movies
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
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
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 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