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Artesian well
Spring
Spring
Water table
Aquifer (rock saturated with water up to water table)
 Spring—Springs occur where an aquifer reaches the surface. They often make lines called spring lines. In the past they provided clean water supplies and were favored places for locating a village.
 Steam—When water boils, it forms a colorless vapor. What we usually call steam is in fact steam that has cooled and condensed back into tiny droplets. It is the droplets of water we see, not the steam. In this picture the true steam lies just beyond the kettle spout.
Steam
Water vapor. It is an odorless and colorless (and thus invisible) gas. Because steam occurs in air that is colder than the steam, some of the vapor immediately condenses and forms tiny water droplets. They are then visible and give steam a smoky appearance.
Steam occurs naturally when superheated water trapped in rocks deep underground finds a quick route to the surface. The water rushes to the surface, and because it is now under less pressure, it immediately begins to boil and turn to steam.
A geyser is a very good example of natural steam, but steam also occurs in places where there are hot springs, fumaroles, and mud pools. Huge amounts of steam are also released during every volcanic eruption. The released water vapor cools in the air above the erupting volcano, turns into cloud, and releases torrential rain.
Steam is used for many industrial purposes, but the most important is to drive the turbines that are connected to electricity generators.
Steam used to drive turbines is produced by heating water using coal, oil or natural gas, wood, refuse, solar power, or through nuclear reactions.
The steam is confined until it has built up considerable pressure, and then it is released into the turbine housing as a jet powerful enough to turn the turbine blades.
Steam is also used in many other industrial processes, for example, in refining petroleum and in making many metals.
In the home steam is used for ironing, for removing wallpaper, and in the form of pressure for cooking food faster than at normal air pressure.
Steam
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