CC PHYSICS Flashcards
TOA IRRADIATION and EMISSION TO SPACE
How much reaches the surface?
Cloud albedo
Aerosols
Path length
Reflected at the surface
PLANK
15°C is different to 40°C and -30°C
Peak of curve moves towards white for hotter and away from white for colder
The 15 micron ‘region’ maintains about 8% of the energy transmitted from the surface whatever the temperature (an assumption)
Ideally, plank curves describe the transmission from a black surface (which is not the Earth’s surface - another assumption)
WHAT HAPPENS WHEN ENERGY IS ABSORBED BY A MOLECULE
A
MOLECULAR ABSORPTION MODES - QUANTUM
Quantum of energy
Photon
Exact amount to raise electron to next quantum level
Femtosecond later electron returns to steady state
Photon released
Scattering - Rayleigh or Mie
MOLECULAR ABSORPTION MODES - NON-QUANTUM
Energy absorbed by electron
Photon
Not sufficient energy to raise to next quantum level
Harmonic or non-harmonic frequency
Vibration or stretching induced
Vibration easier than stretching
Energy absorbed by molecules which then have more energy
More energy, more movement, temperature increases
Work done?
SPECTRAL LINES (SL)
Distinct lines corresponding to FREQUENCY and therefore temperature
Power is a measure of AMPLITUDE
Amplitude is near-infinite at the Sun and minuscule at Earth‘s surface
But the frequency of the SLs is the same
SL and INTERACTION WITH ELECTRONS
Think of electrons connected to nucleus by springs
Free to vibrate or stretch
Natural harmonic
SL frequency with corresponding harmonic
Absorbed by electron
SL frequency NOT on same harmonic
No interaction therefore molecule not seen by the SL energy
