The Four Spheres

1. Biosphere All life from the simple bacterium to the complex human being, belongs to the biosphere

Term was coined in 1929 by a Russian scientist – means life-zone Divided into separate but interdependent units called ecosystems, which are well defined habitats hosting systems of interacting organisms Continuation of life depends on the constant recycling of chemical ingredients called nutrients

Nutrient Cycle 1. Plants feed on carbon, nitrogen, sulphur, potassium and phosphorous. 2. Animals use oxygen to breathe, and they consume the food produced by plants from the other nutrients. 3. When animals die, they in turn are converted into a compost that enriches plant life.

4 Cycles of Biosphere Carbon Cycle Nitrogen Cycle Oxygen Cycle Water Cycle

2. Lithosphere Modern geologists know that the Earth is about 4.6 billion years old Its surface has been changed and reworked repeatedly by simple processes that take hundreds of years to show their effects. Its also highly dynamic because it can change suddenly through events such as earthquakes, volcanoes and floods. E.g. rock cycles, plate tectonics

3. Atmosphere Both the atmosphere and Earth’s oceans are in constant motion. Movement of air and water largely determines weather and climate which controls the distribution of life.

Motion is caused by two processes: 1. The uneven and unequal heating of Earth’s land forms and oceans 2. Earth’s rotation on its axis and its orbital revolution around the sun.

4. Hydrosphere Consists of all the waters of Earth’s surface Flow patterns called ocean currents are wide streams of water that flow in a definite direction within a particular ocean. Ocean currents are driven by the wind and the energy of the sun Tides are powered by the gravitational pull of the moon and sun