Ecosystem

an ecological community that includes all organisms which occur naturally within a specific area.

Taken from Dictionary of Science

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The term ecosystem refers to the combined physical and biological components of an environment. An ecosystem is generally an area within the natural environment in which physical (abiotic) factors of the environment, such as rocks and soil, function together along with interdependent (biotic) organisms, such as plants and animals, within the same habitat. Ecosystems can be permanent or temporary. Ecosystems usually form a number of food webs.

Taken from Wikipedia

Joint

1 in geology, fractures in rock that may occur as parallel sets or, more commonly, in an irregular and less systematic manner. Where a set of joints can be identified, it can usually be related to tectonic (that is to do with deformation of the Earth) stresses and the geometry of the rock body. There are several types of joint: unloading joints, which are caused by the release of stress on rocks at depth as overlying rocks are removed by erosion; cooling joints, which occur in igneous bodies; and joints that are related to regional deformation (on a wide scale).

2 In biology, the point at which bones and the surrounding tissues meet. They may be fixed joints (as in the cranium), slightly movable (e.g., joints in the spine) or freely movable (e.g., knee, arm). The movable joint types also differ -- ball and socket (hip) or hinge (elbow).

Taken from Dictionary of Science

Jet Stream

a high-speed westerly wind in the region of the tropopause. The principal jets are the polar front and subtropical jets, which occur at heights between 10 and 15 km. The winter jet stream occurs between 50 and 80 km in the upper STRATOSPHERE. The wind speeds can reach 300 km/h. The air streams move north and south of their general trend, in surges, which are probably the cause of depressions and anticyclones. There are a number of separate jet streams, but the most constant is that of the subtropics. Jet stream speed and location are of importance to high-flying aircraft.

Taken from Dictionary of Science

Water

hydrogen oxide (H20), a compound that is found everywhere. It can occur as solid, liquid and gas phases. It forms a very large part of the Earth's surface and is vital to life. It occurs in all living organisms and has a remarkable combination of properties in its solvent capacity, chemical stability, thermal properties and abundance.

Taken from Dictionary of Science