Tuesday, August 31, 2010

Biosphere and atmosphere


All the ecosystems of the Earth consists of a functional unit called the Biosphere (spheres of life). The unity of animate and inanimate nature is not limited to ecosystems, but also extends to the entire planet Earth. Biosphere consists of other parts of the Earth's sphere inhabited by living beings:

* Atmosphere, a layer of air that makes the peripheral lining of our planet;
* Hydrosphere, the water layer of the Earth and
* Lithosphere, the outer, surface, hard cover of the Earth.

                             In this picture we see the top of atmosphere

The atmosphere is a gaseous layer around the Earth or another celestial body.
Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains about four fifths nitrogen and one-fifth oxygen, with the amounts of other gases in traces. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

The atmosphere does not end abruptly. It slowly becomes thinner and gradually disappear in the universe. There is no definitive boundary between the atmosphere and outer space. Three-quarters of the mass of the atmosphere lies within 11 km of the planet's surface. In the United States to persons who travel above an altitude of 80 km called the astronaut. Height of 120 km marks the boundary where atmospheric effects become apparent during the spacecraft entering the atmosphere. It is also often a limit of the atmosphere and the universe takes the Kármán line at a distance of 100 km from the surface.

 Layers of the atmosphere:

-Exosphere
-Thermosphere
-Mesosphere
-Stratosphere
-Troposphere



Saturday, August 28, 2010

Biosphere history

The term biosphere was first used by a geologist named Eduard Suess in 1875. He defined biosphere as “the place on earth's surface where life dwells". Vladimir I. Vernadsky refined the definition in 1926, placing the biosphere concept in its current position as one of the spheres in Earth Systems Science. The biosphere is the life zone of the Earth and includes all living organisms: the trees in the park, the birds in the air, fish in the rivers and oceans, the fly on your wall, the viruses that make you sick, bacteria in the trash can, mold on the bread, your pets, and even you and all your friends. The biosphere also includes all organic matter that has not yet decomposed (rotted). The biosphere is interconnected in the other Earth system spheres (Atmosphere, Lithosphere, and Hydrosphere)
Biosphere.



By volume, most of Earth’s biosphere is cold and marine, with 90% of the ocean’s waters at 5°C or colder. Fully 20% of Earth’s surface environment is frozen, including permanently frozen soil(permafrost), terrestrial ice sheets (glacial ice), polar sea ice, and snow cover.


The biosphere has evolved since the first single-celled organisms originated 3.5 billion years ago under atmospheric conditions resembling those of our neighboring planets Mars and Venus, which have atmospheres composed primarily of carbon dioxide. Billions of years of primary production by plants released oxygen from this carbon dioxide and deposited the carbon in sediments, eventually producing the oxygen-rich atmosphere we know today. Free oxygen, both for breathing (O2, respiration) and in the stratospheric ozone (O3) that protects us from harmful UV radiation, has made possible life as we know it while transforming the chemistry of earth systems forever.

The biosphere is a core concept within Biology and Ecology, where it serves as the highest level of biological organization, which begins with parts of cells and proceed to populations, species, ecoregions, biomes and finally, the biosphere. Global patterns of biodiversity within the biosphere are described using biomes.

Biosphere I's total surface area is about 197,000,000 square miles. Approximately 75% of of this is covered in water. The other 25% is divided primarily into seven major land masses or continents. On each of these continents exists the various necessities of life, including air, water, soil, and food. However, the ecosystems that are able to survive and produce on each continent vary widely.

The Earth is a complex balance of her ecosystems. It is the first biosphere, and thus obviouly the model for Biosphere II. Earth contains six ecosystems, including marshes, farmland, savannahs, deserts, oceans, and rainforests. Biosphere I contains countless different plant and animal species, as well as a wealth of minerals and fossil fuels. The basis of life within the Biosphere is mutation and natural selection as forms of self-preservation.