Insolation & temp - chap 4 Flashcards
What drives atmosphere + weather/climate
unequal warming of Earth by SUN
Sun = ultimate source of energy –> nuclear fusion
Type of energy sun provides
electromagnetic radiation (radiant energy)
Inverse Square Law
Energy decreases with distance SO twice distance means 1/4 energy
Earth only receives tiny portion of total solar energy BUT 1 minute of solar radiation hitting earth = humanity’s yearly energy usage
Types of EM radiation
1) Visible: .4-.7 micrometers, 47% solar radiation = visible (ROYGBIV)
2) UV: .01-.5 micrometers, 8% solar radiation, most absorbed in ozone layer
3) .7 to 1000 micrometers, Sun emits near infrared (short waves), Earth emits thermal infrared (long waves)
diff between shortwave and terrestrial radiation
shortwave - visible, UV, IR, emitted by Sun (more energy = more damage)
terrestrial - only thermal infrared, referred to as LONGwave
ten basic heating and cooling processes
1) radiation
2) absorption
3) reflection
4) scattering
5) transmission
6) conduction
7) convection
8) advection
9) adiabatic cooling and warming
10) latent heat
Radiation/emission
process by which electromagnetic energy emitted from object
- hotter object = more intense radiation + shorter wavelengths
all objects emit radiation
blackbody radiator
body emits maximum possible amount of radiation at all wavelengths i.e. sun/Earth
atmosphere NOT blackbody
Absorption
EM waves assimilated into object (absorbed)
- EM waves force electrons/molecules to vibrate more –> increase in internal energy –> increase in temp
good radiators = good absorbers, vice versa
darker object = better absorber
Reflection
bounce back electromagnetic waves
deflects back to space at same angle + initial wavelength
albedo
reflectivity of object/surface as %
Scattering
Deflection + redirection of light waves caused by gas molecules/particulate matter (only changes direction NOT wavelength of energy)
shorter wavelength –> more readily scattered
Rayleigh vs Mie scattering
Rayleigh –> blue/violet scattered most –> why sky blue
Mie –> when lots of suspended aerosols in sky –> even scattering of wavelengths –> sky gray
Transmission
Electromagnetic waves pass completely through medium
*objects vary in how much they transmit (opaque –> less, clear –> more) BUT also in what types of radiation they transmit
ex: glass readily allows shortwave radiation to enter, not longwave to exit so cars get hotter
Greenhouse effect
atmosphere transmits incoming SHORTWAVE radiation from sun but greenhouse gases do not let LONGWAVE TERRESTRIAL radiation transmit out (often re-radiate longwave back to Earth surface –> warms it up)
Keeps troposphere warm –> important for life