About Water (H20) – part 2
by: Dr. James Sangster
By: Dr. James Sangster
PROPERTIES OF WATER
Like any pure substance, water can exist in three forms or states:
1 – As a gas or vapour in the atmosphere or below ground.
2 – As a liquid, in the atmosphere, on the surface or below ground.
3 – As a solid, in the atmosphere, on the surface or below ground.
Water can spontaneously transform from one physical state to another under favorable conditions.
By doing so, water will continually react and move from one environment to another, always present.
Therefore, the flow of water between the oceans, atmosphere and the land is endless, making water finite.
Water on Earth does not increase or decrease but has been continously recycled since creation.
This continuous recycling is better known as the Earth’s Water Cycle.
THE WATER CYCLE
It is now well known quantitatively how Earth’s water is distributed geographically and above,
on and below the surface of the earth.
Water exists in three forms; each form can convert to another form spontaneously.
As a result, water recycles in its various states above, on and below the surface.
Distribution of Earth’s Water
The geographical distribution of Earth’s salty and freshwater varies enormously.
It is easier to grasp this fact if the same data are presented in two ways:
(1) source quantity as a percentage of Earth’s total water, and
(2) as a diminishing cascade bar graph.
The changes in the states of water are shown in this diagram.
Not all these changes are equally important in the recycling process.
The main changes, in practice, are briefly described here. -V8
The atmosphere may contain water in all three states.
Water vapour is invisible, but its presence can be quantified by relative humidity data.
If it forms very small droplets, too small to fall to earth as rain but remains suspended as clouds.
Water vapour close to the ground may condense as dew, frost or fog.
When water vapour is cooled, it condenses (at lower altitudes) to liquid.
At higher altitudes (lower temperatures) it condenses to ice clouds.
Under the right conditions, water in the atmosphere will fall to earth as rain, snow or hail.