GEOS 24705/ ENST 25500 U. Chicago Mar 2011

Lecture 2 Earth’s energy flows II

Where to get practice in estimation / approximation?

Where to get practice in estimation / approximation?

Los Angeles (34 N)

Portland (44 N)

Anchorage (61 N)

Agenda  for  this  lecture  Build  up  to  calcula,ng  whether  hydro  and  biofuels    

can  power  the  modern  world  

•   Sunlight  and  IR  radia/on    (why  "it  all  ends  up  as  heat"  isn't  quite  right)  

•   Efficiency  –  defini/ons  

•   Energy  flow  #1:  hydrological  cycle  efficiency    

•   Pre-­‐industrial  human  energy  needs    

(energy  to  sustain  life)  

•   Energy  flow  #2:  photosynthesis  efficiency  

•   Modern  energy  use  and  change  from  preindustrial