Water--Cool, Clear, Water

An alien race looking at the Earth from space would classify our Earth as a water planet, nearly 70% of its surface is covered by water and we human inhabitants are 60% water. Unfortunately for thirsty Earthlings, all but 0.3% is too salty to use. To put that in a way I can understand, if ten glasses of water represented all the water on Earth, only one-third of one of the glasses would represent all the fresh water we have. Considering there are now over six billion humans and counting, each of us shares fewer and fewer amounts of drinkable water.

So what kinda numbers are we talking about? Well, there are about two billion cubic miles of fresh water, mostly in lakes, rivers and ground water. Ground water is water that is underground and usually available by wells or springs.

If we distribute the fresh water equally among the six billion or so people alive today it comes out to about 330 million gallons each. Of course, a lot of the fresh water is used by industry, washing cars, taking showers and all the stuff we use fresh water for besides drinking.

The World Health Organization states that each person needs 264,000 gallons per year or about 700 gallons per day for basic human needs. That comes out to 1,500,000,000,000 gallons per year or one and a half trillion gallons.

In the U.S each of us personally uses twice the world average and we use 408 billion gallons each DAY for all purposes. Over one- fourth of that amount is used by only three states, California, Florida and Texas.

So, it is pretty obvious that somebody is going get pretty thirsty, by 2025 it is estimated that 48 countries, 22 of them sub-Saharan, will be critically short of fresh water.

Next week we'll talk about how fresh water gets recycled and how we can make more of 'the new liquid gold'.

The Spheres of the Atmo-sphere

This week I'm going to write about the spheres of the atmosphere, but only four of the more important ones---the troposphere, stratosphere, mesosphere and the thermosphere.

The sphere we spend most of our time in and where most of the weather happens is the troposphere. This is the lowest layer of the atmosphere and extends up from 5 to 10 miles. This sphere is characterized by a decrease in temperature as you go higher and is the layer where most of the atmosphere’s water vapor is found. So, it’s not surprising that most of the clouds are found here.

The layer just above the troposphere is the stratosphere which is characterized by an increase in temperature as you go higher. Passenger jets like to fly as near to this layer as they can get as it is above most of the weather in the troposphere. The stratosphere extends from the upper boundary of the troposphere to an altitude of about 31 miles. It is in this layer that most of the ozone in the atmosphere is found. You’ve probably heard about the ‘depletion of the ozone layer’. The stratosphere is where most of this endangered molecule, ozone, is found. The importance of ozone is that it absorbs ultraviolet light before it reaches the Earth’s surface where it can do mischief to living things—like you and me.

Above the stratosphere is the mesosphere. This layer stretches between 31 and 50 miles and again you find a temperature decrease as you go higher. It is in this sphere that most meteors burn up, the ‘shooting stars’.

The next layer is the thermosphere. This layer begins about 50 miles up to around 435 miles. Somewhere in here is, I think, where the old ionosphere used to be, but I guess they don’t call it that any more. As the old name implied this layer has in it ionized gases .They get that way because radiation from the sun knocks loose one or more electrons from atoms of gas. These ionized atoms have an electric charge and can therefore reflect radio waves of certain frequencies allowing, for instance short wave radio waves, to travel thousands of miles. This was obviously more important before the days of communication satellites.

Nature doesn’t care what we call these various parts of the atmosphere; they are just names we give things so we all know what we are all talking about. And just because you know the name of something doesn’t mean you know anything about it. Hopefully now the names mean more and the next time your on an airplane and the pilot tells you that you’re flying at a cruising altitude of 35,000 feet you’ll know you may be in the lower reaches of the stratosphere and probably won’t have to worry about bumpy air until you descend into the troposphere.

Why is the Earth Still Hot?

According to the folks who know a lot about such things, the Earth is over four and a half billion years old. So, it does make you wonder why it is still so hot. There are still many places where volcanoes shoot up molten rock and geysers of boiling water erupt. Some countries like Iceland even use this heat for heating and power.

If you go down into a deep mine, you will find that the temperature increases about one degree Fahrenheit for every 60 feet you descend. If you do the arithmetic that would make the core of the Earth one hundred thousand degrees F., which it is not, your thermometer will read only around eleven thousand degrees. So, the degree of heating must slow down at a level much deeper than we can dig. But, that is still hotter than the surface of the sun which comes in around ten thousand degrees F. Where does that heat come from?

The major source of heat is from the decay of the radioactive isotopes of Thorium, Uranium and Phosphorus occurring naturally in the Earth’s mantle, an 1800 mile thick layer lying under the Earth’s crust—the part we live on.

An isotope is another form of the same element differing only in the number of neutrons. Chemically they behave the same, but the additional neutrons can make the nucleus of some elements unstable. This instability results in the emitting of rays or particles in an attempt to become more stable. Nature doesn’t like instability.

When the radioactive isotopes of Uranium, Thorium and Phosphorus decay they release heat in the same way as the Uranium isotopes do in a nuclear reactor.

This heating will not go on forever. In a few billion years the isotopes heating the mantle will all have decayed and the planet will cool and become as cold as the moon, but by that time the sun will have become a red giant, its surface extending well beyond Earth’s orbit.

That will heat things up again and if we’re still around we had better have moved out of the neighborhood.