Processes and Cycles Earth as a System Four

Processes and Cycles Earth as a System

Four Spheres of the Earth 1. Geosphere: the solid Earth 1. The geosphere contains the most matter. 2. Hydrosphere: the Water 1. Water covers about two-thirds of the Earth, 71% 2. 97% is salty ocean water. 3% is fresh. 3. Atmosphere: the Air 1. 78% nitrogen, 21% oxygen, 1% other 4. Biosphere: all the living things 1. Mostly on the crust and in the hydrosphere.

Matter Cycles Between the Spheres

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.

Carbon Cycle

Important Processes �Photosynthesis: • Plants make food from CO 2 and H 2 O. �Cellular Respiration: • Living things burn food, making CO 2 and H 2 O. �Nitrogen Fixation: • Nitrogen gas (N 2 ) is changed into more useful forms by bacteria in plant nodules, lightning, and fertilizer companies.

Nitrogen Cycle

Phosphorus Cycle � Florida has many phosphate mines.

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.

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

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.

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.