1. Processes and Cycles
Earth as a System

2. Four Spheres of the Earth
Geosphere: the solid Earth
The geosphere contains the most matter.
Hydrosphere: the Water
Water covers about two-thirds of the Earth, 71%
97% is salty ocean water. 3% is fresh.
Atmosphere: the Air
78% nitrogen, 21% oxygen, 1% other
Biosphere: all the living things
Mostly on the crust and in the hydrosphere.

4. Matter Cycles Between the Spheres

5. Reservoirs
In each cycle, we see reservoirs where different substances are stored in large quantities most of the time.
Living things are reservoirs as well.
Humans affect all the cycles when we move resources out of reservoirs.

6. Carbon Cycle

7. Important Processes Photosynthesis: Cellular Respiration:
Plants make food from CO2 and H2 O.
Cellular Respiration:
Living things burn food, making CO2 and H2 O.
Nitrogen Fixation:
Nitrogen gas (N2 ) is changed into more useful forms by bacteria in plant nodules, lightning, and fertilizer companies.

8. Nitrogen Cycle

9. Phosphorus Cycle
Florida has many phosphate mines.

10. Convection Convection is a process that moves heat around.
When matter is heated, it expands. Its density drops.
The lighter hot material rises. Cooler material drops.

11. Convection
Convection happens in the Earth’s mantle, in the oceans and in the atmosphere.

12. Energy in the Earth The center of the Earth is very hot.
This heat was produced when the Earth was formed. As big chunks of rock collided, their kinetic energy became heat. (Gravitational energy  heat.)
More heat was produced by radioactive decay of big atoms.

13. External Energy Solar radiation is constantly arriving on Earth.
This energy is needed for all life in the biosphere. Plants use solar energy to make food.
Gravity from the sun and moon also give energy to the Earth by providing tides that move ocean water.