The sub-terrestrial

1. Atmosphere

The atmosphere is the gaseous part of the Earth, and is thus the outer layer and less dense planet. It consists of several gases that vary in amount depending on the pressure at various altitudes. This mixture of gases that form the atmosphere receives the generic name of air. 75% of atmospheric mass is in the first 11 km high from the sea surface. The main constituent elements are oxygen (21%) and nitrogen (78%).

2. Hydrosphere

The hydrosphere or hydrosphere (Greek hydros, water and sphaira: field) described in the Earth Sciences the material system consisting of the water is low, and on the surface of the Earth.

The water that forms the hydrosphere is divided between various compartments in descending order of volume are:

ü The oceans, which cover two thirds of the earth's surface with a typical depth of 3000 to 5000 meters.

ü The glaciers that cover part of the land surface. Especially the two ice sheets of Greenland and Antarctica, but mountain glaciers and volcano, many smaller thickness at all latitudes.

üSurface runoff, a very dynamic system formed by rivers and lakes.

üGroundwater, which is embedded in porous rock more or less universal.

üEn la atmósfera en forma de nubes.

üEn la biosfera, formando parte de plantas, animales y
seres humanos.

3. Geósfera

The geosphere is the structural part of the Earth that extends from the surface to the interior of the planet (about 6740 km). This layer is characterized by a rock structure that supports the rest of the other terrestrial systems, as the biosphere and atmosphere, located these on the most superficial.

4. Biosfera

In ecology, the biosphere and biosphere is the material system consists of a group of living beings own planet Earth, along with the physical environment around them and they help shape. This meaning of "wrapping live" Earth is the most widely used, but also speaks of biosphere times to refer to the space within which life develops, the biosphere is also the whole of the lithosphere, hydrosphere and the atmosphere.

The biosphere is the global ecosystem. At the same concept we refer to other terms that can be considered synonyms, as ecosphere or biogeosfera. It is a collective creation of a variety of organisms and species interacting with each other, form the diversity of ecosystems. It has properties that allow us to speak of it as a great living being, able to control, within limits, their own state and evolution.