THE OCEAN SCHOOL
Physical Science – Oceanography – Water
Earth’s most unique property is its abundance of water. Its bright blue color dominates our planet. Rivers and lakes receive the excess waters of our clouds. Snow covers mountains. Thick ice encases Earth’s poles.
We live on continental islands in the midst of one great inter-connected body of water, filled with great numbers of creatures adapted to their watery world. Our ocean covers 140 million square miles (roughly ¾’s of our Earth’s surface). It averages two and ½ miles deep, and contains 320 million cubic miles of volume, a volume containing an almost unimaginable variety of unique and amazing creatures. Water is the basis of all life and its processes.
Why Earth is blessed with its volumes of H2O remains a mystery. Our space explorations indicate water once existed on Mars, and the moons of Earth, Jupiter and Saturn. Haley’s comet may contain immense volumes of water. But Earth alone, in this part of the cosmos, contains a liquid ocean.
The Unusual Molecule:
Water is a simple molecule with exceptional properties – properties that make life on earth both unique and possible. Chemically the water molecule is made up of one atom of oxygen and two atoms of hydrogen, atoms that easily fuse together into exact angles that aid easy connection to other water molecules and substances. (Chemists call this precise 104.5 degree angle a dipole – the molecule is ‘polar’. H2O molecules are extremely stable whether in frozen, liquid or vapor states. . Because of each molecule’s positive and negative ends, water readily shares its hydrogen atom with other molecules creating a stable, flowing liquid at Earth’s normal temperatures. Because of its electron charge water easily attracts other substances such as nutrients while flushing away wastes. So air and water toxins and pollutants easily attach to water in the environment. Pure water is very hard to find.
The hydrogen bonds pack the molecules so close that liquid water has a higher density than other liquids. Most living creatures are composed primarily of water, and much of Earth’s life processes are built upon liquid water. It’s high boiling point of 212 F, and low freezing point of 32 F, allows this critical life substance to function in Earth’s mild temperature ranges. However, as water cools and contracts, a most amazing thing happens.
When water freezes its hydrogen properties arrange the water molecules into hexagons (the beautiful and unique snow and ice crystals) with an empty space making a solid with a low density. Uniquely solid frozen water is actually lighter than its liquid state. Because of this unique hydrogen bonding, ice floats!
Instead of our lakes and oceans being frozen from the bottom up, our low-density ice floats on liquid water. Instead of our waters being frozen solid with a thin layer of liquid water on top, life in our waters is protected underneath the floating ice, which insulates the life-giving water from even the coldest temperatures. Instead of a solid block of ice like on neighboring planets, Earth’s temperature range and water’s unique properties allow for our variations of climate and weather.
As water cools, or as salt is added, water’s density - its relative weight increases. As water warms, or salinity is reduced, its weight decreases and it floats above the colder, deeper waters. These simple relations power the flow of the great ocean currents as our world attempts to stabilize these differences. The movements of these cold, deep waters and warmer upper level waters generate our large weather systems that then flow across the land – where most humans live - and creates our climates.
Water has a high heat capacity. Its temperature is uniquely stable. It takes more energy to heat up a gram of water than it takes to heat up a gram of metal. For example water requires 30x the energy it takes to heat up a gram of gold one degree! So this amazing molecule also directly moderates our temperature ranges. Think how much greater are the daily temperature fluctuations in the deserts or high mountains. The massive volume of ocean water and its resistance to temperature change reduces our coastal temperature changes; while water’s temperature stability allows the development and growth of our many unique life forms requiring a stable environment to develop. If Earth was not a water planet, our temperatures would fluctuate by several hundred degrees Centigrade, instead of the moderate –50 to +50 C we currently experience.
Water also has a high vaporization heat. It takes a lot of energy to change from liquid into vapor, into a gas. As this transition takes place, the necessary energy is drawn from the environment, cooling it in the process. Thus coastal areas have a more moderate climate than inland areas. When water condenses again – when it returns from a gas to a liquid – a great amount of this energy is released into the atmosphere driving the world’s powerful weather systems.
We take water so for granted. Its profound simplicity and basic properties are often over looked. When next you take a drink think about the importance of water to your very existence. One more thought. Water is H2O. Where does the oxygen atom come from (more later). That hydrogen atom was created at the start of the universe. So when you are drinking that glass of water, you are drinking something billions of years old!
Further Reading
Waller G. 1996 SeaLife: A Complete Guide to the Marine Environment. Smithonian Institution Press, Washington
Sylvia Earle, 2001. National Geographic Atlas of the Oceans, the Deep Frontier. National Geographic Society, Washington D.C.
Links
Underwater Times http://www.underwatertimes.com/oceans/oceans.php
Study topics:
Freeze water
Condense steam
Compress water
Cleaning water
Float water
Actions that make a difference:
What you can do:
Conserve Water in every use.
Plant native vegetation that doesn’t need much water
Install water-saving showerheads, faucets, and flushes
Consider gray-water systems for your house
Don’t wash your vehicle or driveway unnecessarily
Pollute as little water as possible with as appropriate a pollutant as possible: soaps, oil, and fertilizer – it all ends up in the ocean.
Don’t use artificial fertilizer on your lawn
Consider not pursuing activities that waste and pollute water
Study disposal of oils
Reduce introduction of gasoline or oil into any lake or ocean
Check your engines for gas and oil leaks
Use biodegradable soaps and detergents
What needs to be done globally:
Expand humans understanding of the scarcity and delicacy of maintaining clean, healthy water for all global systems and needs
Develop realistic models of our multiple uses of each water molecule and how to maintain this life giving asset for future uses
Develop realistic model of true costs of current and planned water uses
Aquifer depletion needs to be reduced
River flow needs should be studied in light of appropriate uses and consumption
Water over-use should be reduced
Develop true costs to the H2O cycle of various manufacturing processes and agricultural crop methods
Hydro-electric dam projects need long range planning and impact analysis on their effects beyond the narrow current analyses
Ocean-dumping of any type in any location should be stopped
Untreated sewage disposal must be addressed
Study appropriate sustainable, natural agricultural methods for industrial farming
Energy sources such as wind and solar need to be evaluated and developed
Clean energy such as hydrogen need consideration for transportation