The Dance of Liquid Water

     Water is the only substance that naturally exists in 3 forms, as a solid (ice), as a liquid (the water we drink) and as a gas (water vapor). Water in the atmosphere exists in all three forms with the vast majority of water being in the vapor form.

Visible water in the air

     Clouds are the visible form of liquid water in the air. Clouds are formed when water vapor in the air condenses into liquid droplets that are so small that they are light enough to float in the air. For this change (condensation) in form to occur, water needs a non-gaseous surface. Physical particles that serve this purpose are known as cloud condensation nuclei (CCN).

     For clouds to be seen, water droplets need to coalesce (combine) into larger droplets. This coalescence typically happens when individual droplets collide as they move through the air. Water droplets combine with some difficulty (a direct result of the hydrogen bonds discussed in my post dated December 4, 2010) as illustrated by the gravity-fueled "dance" of a drop of liquid water that is falling onto a larger liquid water body, in the video below:

For clouds to produce rain drops, the CCN-created water droplets need to grow about a million times larger through numerous collisions.

Invisible (to the human eye) liquid water in the Air
     Liquid water droplets that are smaller than 0.02 mm in size that find a physical particle suitable for formation (from water vapor), can also be trapped between particles and stay in that 'normal' state for extended periods of time. Aerosol particles, by holding water droplets captive, contribute a continued and longer-term worsening impact on global warming.
     Initiatives that are efficient and effective at extracting this "trapped" water from the atmosphere and inhibiting continuing entrapment would produce both fresh drinking water and reduce Global Warming.    


References:
http://www.atmosphere.mpg.de/enid/850ac2615b35b9f50abbc96fa4273dbb,0/1__Clouds/-_Water_in_the_atmosphere_25n.html
http://www.youtube.com/watch?v=6KKNnjFpGto&feature=BF&playnext=1&list=QL

Amount of Water in the Atmosphere

We know, all too well from personal experience, that the amount of water in air varies quite a bit over a day, over a month and over a year. We can sense humidity levels and have experienced how we sweat more and the sweat does not evaporate when air humidity is high. 


3413 Trillion US Gallons

     The US Geological Survey estimates the total amount of water in the atmosphere as 3,100 cubic miles or (at 1 cubic mile = 1.10111715 × 10¹² US gallons) 3413.463165 × 10¹² US gallons.

     This is only about 0.001% of the total water on Earth .

Temperature & Humidity control amount
     The specific amount of water in the air varies with temperature and humidity.
     At 30 degrees Celsius, the amount of water varies from 0 grams per cubic meter in dry air to 30 grams per cubic meter (0.03 ounce per cubic foot) when the air is saturated.

        At a temperature of 50 degrees Celsius, there are 83 grams per cubic meter (0.08 ounces per cubic foot) when the humidity is 100% 

Relative humidity	20 %	40 %	60 %	80 %	100 %
+50 °C	16.6	33.2	49.8	66.4	83.0
+40 °C	10.2	20.5	30.7	40.9	51.1
+30 °C	6.1	12.1	18.2	24.3	30.4
+20 °C	3.5	6.9	10.4	13.8	17.3
+10 °C	1.9	3.8	5.6	7.5	9.4
0	1.0	1.9	2.9	3.9	4.8
-10 °C	0.5	0.9	1.4	1.9	2.3
-20 °C	0.2	0.4	0.5	0.7	0.9

3 ways water ends up in the air 
     Evaporation - the process by which water is converted from liquid to vapor state and added into the air. Nearly 90% of the water in the atmosphere is due to evaporation from oceans, lakes and other large bodies of water
     Transpiration - The process  by which plants release water vapor directly into the air. This process accounts for nearly 10% of the water vapor in the atmosphere
     Sublimation -  The process by which ice changes directly (without entering the liquid state) into water vapor that ends up in the air. This is why ice, that has been in your freezer or the ice chest for a long time, looks 'different', tastes hollow, feels 'less cold' and crushes easily.

Mean Annual Precipitation = 1 Meter

    The mean annual precipitation every year is about 1 meter (about 3 feet and 3 inches). As this is water vapor condensed from regions close to the surface, it gives us a measure of the amount of water that circulates in and out of the atmosphere on an annual basis.

     Attempts to extract this volume of water through human endeavour would keep the hydrological cycle in harmony with its natural performance

99% of water is close to ground level

     75% of the air in the atmosphere and 99% of all the water in the atmosphere lie in the first 9 miles (15 kilometers) above the ground. This part of the atmosphere is called the Troposphere.

     The composition of the troposphere is uniform throughout its height (i.e. does not vary with elevation above the Earth) except in one way, namely, the proportion of water vapor is greatest closest to the ground and decreases as elevation increases.

References:

http://ga.water.usgs.gov/edu/watercycleatmosphere.html

http://en.wikipedia.org/wiki/Water_vapor
 http://en.wikipedia.org/wiki/Troposphere
http://books.google.com/books?id=oh8lqM5obuYC&pg=PA156&lpg=PA156&dq=water+vapor- 

What do Jesus Lizard, Life and Micro-Habitats have in common?

             

Basilisk, the lizard in the video is also called the Jesus Lizard because it can walk on water for about 15 feet when it's weight is about 250 grams. The lizard is able to accomplish this feat by trapping air and water bubbles in a web formation under its feet that assist it to stay above the water surface as long as it keeps moving.

This ability of the Jesus Lizard is a result of the hydrogen bonds that connect water molecules. As shown in the diagram below, the positively charged hydrogen atoms are attracted to the negatively charged oxygen atoms. This  

                         

attraction creates a very strong bond, that at the water's surface is responsible for the strong surface tension of water that also assists the Jesus Lizard to walk on the water's surface.

Life Requires Liquid Water

Imagine what would happen if water did not exist as a liquid over the range of temperatures that humans and other life forms can endure. If water at 98.6 degrees Fahrenheit (37 degrees Celsius) was a gas, imagine what would happen to the blood in our veins, the sweat we release, the tears we shed and the rest of the 68% of us that is water. Likewise, imagine if water at 96.6 degrees Fahrenheit (37 degrees Celsius) was a solid. Our saviour, and that of all water-based life, is the Hydrogen Bond.

Hydrogen bonds make water molecules stick together strongly enough to make water freeze at temperatures much lower than it would without them and make water boil at temperatures much higher than that if these bonds did not exist. Scientists tell us that water that boils at 100 degrees Celsius would, without the stickiness of hydrogen bonds, boil at temperatures well below -90 degrees Fahrenheit (-70 degrees Celsius). Life as we know it would not exist without the hydrogen bond.



Water Micro-habitats in the Atmosphere

Hydrogen bonds create the surface tension which, in turn, presents a barrier keeping air and water apart. This separation creates micro-habitats - small regions that contain some special features that suit one (or more) organisms better than it suits other organisms - in the atmosphere. The impact on air-borne organisms when water is extracted from air using biological means needs much further research and study.