Source of Water on Planet Earth

The Deuterium/Hydrogen ratio of water on Earth suggests that all the water came to Earth on meteorites,

The Deuterium/Hydrogen Ratio

Source - nasa.gov

Much of the Earth's hydrogen exists in two isotopes, namely, the commonly available Hydrogen and as "heavy" hydrogen (Deuterium). 0.015% of ocean water is heavy water i.e. made up of deuterium and oxygen.

Our bodies also contain about 5 grams of deuterium which is thought to be harmless to us in that quantity. At higher levels heavy-water inhibits cell function and is, thus, harmful to the human body.

Meteors and Comets

Comet Lulin
Source - Guardian.com.uk

Both meteors and comets contain water. Vaporization of the water, as a comet comes close to the sun gives comets their distinctive 'tail.

Meteors, on the other hand, contain only small quantities of water that land on Earth, if the meteor is not vaporised in the atmosphere. 

Meteors are named for their originating star and the pieces that land on Earth are called meteorites.

Meteorite showers occur almost annually.

Differences in Water carried by Comets and Meteors

Source - Science Magazine 10 Aug 2001
The Origin of Water by Francois Robert

Analysis of the water contained on meteorites and comets clearly shows that meteorites contain water in the same deuterium/hydrogen ratio as exists on Earth. 

The water on Earth, thus, originated in meteorites.

Water Helps Us "see" Air

Just like fish are unaware of the water they live in, we humans take our atmosphere for granted. However, water in the atmosphere periodically reminds us of air's existence especially when there is no wind that we can feel

Water droplets in the atmosphere

Source - nationalgeographic.com

Clouds are water droplets and ice crystals suspended in the air. 

Water vapor condenses to liquid form when the air becomes saturated and condensation nuclei are available to catalyze condensation.

The two common ways for saturation to produce clouds are:

Add moisture to the air through evaporation
Cool the air to its dew point

Artificial Clouds

Source - Wikipedia.org

Source - skystef.be

Carbon-dioxide and water vapor are the primary products of hydrocarbon combustion. 

Contrails, visible condensation trails, are formed behind aircraft when water vapor in the air and/or in engine exhaust condense. 

Contrails are more visible at higher altitudes where the temperature is low (-40 degrees) and where the reduction in pressure behind an airplane cools water vapor that can condense onto particulates in the exhaust.

Seeing our Breath

Source - sixmartinis.blogspot.com

On a cold day, we can "see our breath" because we exhale water vapor that becomes chilled to the point where the vapor condenses into a fog before our eyes.

Song and Dance for Raindrops - Superstition or Science?

Many human communities have a long-standing belief that song and dance can deliver raindrops from the gods.

Nucleation of vapor into liquid droplets
Air may be under-saturated, saturated or super-saturated with water vapor. As 2% of the moisture in the air is always in the liquid state, the 98% of water in vapor form comes into occasional contact with water droplets in the air.
Thermodynamically speaking, both the under-saturated and the saturated conditions are stable, in the sense that the vapor and liquid states continue to coexist indefinitely unless a physical disturbance occurs. 
The super-saturated condition, however, is thermodynamically unstable i.e. the excess vapor in the air is actively wanting to exit from the air and is prone to doing so in liquid water form. In fact, if the super-saturated vapor comes into contact with liquid water droplets and continues to stay in contact for less than a second, this vapor condenses immediately to grow the liquid droplet.


Song and Dance create motion in air
Loud continuous sounds cause air to move (as sound waves cause tiny movements in the air) as does dancing that moves air in chunks the size of our human bodies. The net amount of physical movement of air is, of course, dependent upon the pitch and duration of the sounds we make and the intensity and continuity of our physical movement.
It is thermodynamically proven that on a cool still night, when air is saturated or super-saturated with water vapor, when this air contains water droplets of a critical size, the right intensity and continuity of sound and human body movement can condense water vapor into fog that eventually turns into liquid rain.


This use of sounds to produce rain is also documented in the rain dances in Africa and the use of yelling in the Yunan mountains of China.

Our Atmosphere is the ONLY source of Freshwater

The ONLY source of 99% of ALL freshwater is water contained in the atmosphere. As 98% of this water is in vapor form, precipitation is the key to delivery of freshwater as rain, snow, dew and mist.

Freshwater - Definition

All water contains dissolved solids.

• Water with dissolved solids that constitute <0.5 parts per thousand, is classified as freshwater
• Water in the oceans contains 30-50 parts per thousand of dissolved solids 

Water and Life on Earth

Life on Earth, of every kind, depends entirely on a complex set of interrelated conditions - the most significant condition is that all cells have to continue to be 'wet' to function. Some cells can survive periods of dehydration but during periods of dehydration, they cannot perform their function.  

All cells reflect the different salt (saline) water environments that exist on Earth. Some exist only in the salt-waters of the oceans while others (including humans) cannot survive without freshwater.

Limited but plentiful resource

There is enough freshwater for all living things that require it. However, the total amount of freshwater available is limited by nature and this amount is more than adequate for all living things that require it. 
The limited supply of freshwater is continuously replenished by the Earth's hydrological cycle.

On an average, only 11 days elapse between the time water evaporates into the atmosphere (mainly from the oceans) and the time it drops at rain after being moved around by wind.

One estimate of global fresh-water distribution

Water source	Water volume, in cubic miles	Water volume, in cubic kilometers	Percent of freshwater	Percent of total water
Lakes, swamps	24,600	102,500	0.29%	0.008%
Rivers	509	2,120	0.006%	0.0002%
Total global fresh water	8,404,000	35,030,000	100%	2.5%
Total global water	332,500,000	1,386,000,000	--	100%
Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.

Amount of Freshwater in the Atmosphere

The atmosphere contains 10.5 billion acre-feet of water at any instant in time. This water is more than 6 times all the water in all the rivers in the world.

The vast majority of freshwater is locked up in glaciers that constitute ice packs at the poles and on mountain tops, in the pores of rocks and underground.