climate

• Climate is the average and variations of long periods of time - 30 years. 
• Weather is the natural phenomena within the atmosphere within the atmosphere at a given time. 
• Factors influencing temperature:

  • Cloud cover
  • Insolation 
  • Humidity 
  • Tilt of axis 
  • Sunspot
  • Atmospheric gas concentration 
  • Heat output of the sun 
  • Distance from sun 
  • Comp of atmosphere 
  • Volcanic activity 
• Ocean circulations consist of sinking cool water, rising warm water and wind. 
• Shallow ocean currents are driven by the sun heating and cooling the planet to create pressure systems, the wind formed from the pressure differences blows over the ocean and drags the water with it. 
• Deep ocean currents are driven by density differences, thermohaline circulations result in density depending on salinity and temperature. 
• Greenhouse gasses:

  • CO2 
  • CH4
  • O3
  • CFCs
  • H2O
  • N2O
• Through time the planets temperature fluctuates. 
• An icehouse phase is when earth has colder than average temperatures. Large ice sheets exist on both poles, the Antarctic ice sheet is 34 my and the arctic is 2 my. 
• There has been 3 icehouse phases in the phanerozoic. During icehouse phases glaciers extend down from the poles. 
• During the Precambrian the earth was covered in ice. 
• Icehouses are unusual and the poles have been ice free for most of time - normally earth would have higher sea levels. 
• Greenhouse phases are defined by a lack of ice coverage and an increase in temperatures. Caused by an increase in the amount of radiation that reaches earths surface or a change in GHG concentration.