Download Earth`s Different Spheres

Earth’s Different Spheres
Fri. April 20, 2012
-There are four different spheres that we will consider when we discuss the Earth’s
ecosystem:
1. The Atmosphere
-a layer of gases that surround the Earth
-The Atmosphere protects living organisms from the Sun’s harmful rays (Ultra Violet
(UV))
-The Ozone Layer filters out UV radiation.
-the Atmosphere insulates the surface of the Earth and reduces temperature
extremes between day and night
-it is composed of 78% Nitrogen (N2), 21% Oxygen (O2), and 1% other gases (H2,
CO2, etc.)
-CO2 and CH4 are responsible for the “greenhouse effect”
1. Sunlight enters the atmosphere, strikes the surface of the earth and warms it
2. The absorbed Energy from the Sun is given off by the Earth in the form of Infra
Red Radiation
2. Carbon Dioxide and Methane trap Infra Red Radiation energy in the
atmosphere.
-it is only a few kilometers thick
-mercury is an example of a planet that does not have an atmosphere. It is an
inhospitable planet that is extremely hot on the side that faces the sun and
extremely cold on the side that faces away
-UV radiation is needed to produce Vitamin D in humans, but can also cause burns,
and then a tan develops when the skin produces melanin (a protection
mechanism from the Sun’s radiation)
-there have been holes made in the Ozone layer (especially around the poles) due
to the usage of chlorofluorocarbons (CFC’s) a few decades ago
Lithosphere
-This is the solid rocky crust that covers the entire planet.
-The lithosphere extends from the highest mountain peaks to the deepest ocean
floor.
-Volcanic activity and earthquakes are disruptions of the lithosphere
Hydrosphere
-We find water in oceans, lakes and rivers, underground aquifers, and in the
atmosphere.
-This is the sum total of all water found on Earth.
Biosphere
-this is the biological component of earth’s systems. It includes all living organisms
(plants, animals, bacteria, viruses)
-the biosphere interacts with and exchanges matter and energy with a ll other
spheres
The Gaia Hypothesis
-James Lovelock proposed this theory in the 1960’s
-He stated that Earth is like a living organism through the interaction of all its spheres