The Physical Environment

An integrated system of four spheres

What are the four spheres?

• Atmosphere– Trophosphere 0-10 miles

• Virtually all water here

• Ozone layer here

• 80-85% of mass of atmosphere

– Stratosphere 10-30 miles– Mesosphere 30-50 miles– Thermosphere >50 miles

• Little known

• Except for water and ozone, composition is fairly constant up to the thermosphere

• Density goes down as you go up

Lithosphere

• Geology

• Crust of earth

Hydrosphere

• Water layer on earth

• Carries heat, moves it pole-equator and vice versa

• Influenced by the Coriolis effect

Biosphere

• Layer where life is

• Deepest ocean - highest mountain tops

• Next week we’ll look at various biomes (specific divisions of biosphere)

• Ecology applies here

Cycles Between the Spheres

• Law of Conservation of Energy - matter cannot be created nor destroyed

• Matter and energy can be transformed into various forms

• Gas-liquid-solid

• Biogeochemical cycles

Abundances

• Life is very different from its environment

Carbon Cycle

• Looks complex; but it is all about withdrawals to and additions from atmosphere

• Withdrawls:– Photosynthesis– 6CO2 + 6H20 + energy ---->C6H12O6 + 6O2– Accumulation into tissues

• Fossil fuels

• Shells = limestone

Oceanic

geological

TerrestrialAtmosphere

Carbon Cycle

• Additions:– Cellular respiration– C6H12O6 + 6O2 ---> 6CO2 + 6H2O + energy– Literally exhalation– Combustion

• Of such fossil fuels

• Global warming = too much CO2 accumulating in atmosphere

Carbon cycles goes through all 4 spheres

• Atmosphere - CO2 gas

• Hydrosphere - CO2 gas, also in tissues

• Now in Biosphere

• When organisms die now tissues become fossilized; part of lithosphere

• Fossil fuels burned releases CO2 gas back to atmosphere