Exactly what is a Green House Gas? With all the attention to global warming, you would expect that people would know what a green house gas is. I will try to shed some light on the subject in this blog.
First off, you need to understand a little about gases and the atmosphere of the Earth. If any of you have ever looked at a campfire, you will have noticed that the smoke "rises". This is a very big deal, but why does it rise? That is the real question. Put very simple, it rises because the smoke is hotter than the surrounding air. It rises in the air like a fishing bobber rises from under the water. but there is more too it. What actually happens is that the air pushes down around the smoke and the smoke goes up much like toothpaste squirts out of the toothpaste tube. With me so far?
The smoke that rises from a campfire is made up of all kinds of gas and particles. It is the particles that one sees in the smoke, but there is both mostly is made up of water vapor and carbon dioxide, but how does it rise since most of the smoke is heavier than air? Now, it gets a little more complicated. If you have ever heard of Avogadro's Number, it is the number of molecules of any gas that will occupy the same space. I feel this is a revolutionary concept and fact. It means that the same volume of a gas will contain the same number of molecules. The only difference is that the same volume of bigger molecules will will proportionate to their molecular weight. I will explain this in a little more detail.
The Earth's atmosphere is made up several gases of different molecular weights. Like a glass of water and oil will separate into layers by gravity, the same thing happens in our atmosphere. Let me give you some numbers.
Gas Atomic # Molecule Weight/Density
Hydrogen 1 H2 2
Nitrogen 7 N2 14
Oxygen 8 O2 16
Water H2O 10
Carbon Dioxide CO2 23
The Earth's atmosphere is 99% a mixture of Nitrogen and Oxygen which means that Carbon Dioxide is over 50% heavier than the Earth's atmosphere.. Now, what is the significands of this?
Now, back to the campfire. Hot air rises, we know that, but what else? For heavier air molecules to rise, they have to be warmer than the other lighter air around them. In the case of the campfire we have that special condition until the smoke rises higher and higher and cools off and stops rising. Why is this key to global warming and greenhouse gases?
If you have ever flown on a commercial airline at high altitude you will notice that the air out side the plane is often well below zero while on the ground it may have been over 80 degrees. That is because the Sun is heating both the air and the ground so that the atmosphere is the hottest down at ground level. With me on that one? This heating of the air next to the ground causes the hot gases that make up the atmosphere rise and they do. The problem is that since the the Carbon Dioxide are heavier than the other air that they have to be a lot hotter before they can rise and get rid of their heat to outer space., but they can't do that because they can not get any hotter than their surround air. The bottom line is that these greenhouse gases keep their heat and stay right down on the ground causing the temperature of the Earth's atmosphere to rise.
A final point about the water vapor. When it get higher and higher it cools down to the point that it turns back into a liquid call "rain" and returns to the ground. Notice that water vapor is much lighter than the other gases in the atmosphere and thus is an important gas to cool the atmosphere and the Earth. As we get more and more Carbon Dioxide into the air, it makes the water vapor more efficient in cooling the atmosphere back down. They never the tell you that do they?
PS--I did not talk about Ozone which is 03. It has a molecular weight of 24 which is a little heavier than CO2. It acts like CO2. Plants grow faster with more CO2 and the vertical turbulence and efficiency of the air in cooling the Earth gets more efficient as the Earth warms. This acts to dampen the impact of more Carbon Dioxide and Ozone in the air. That mean that it gets harder and harder to raise the temperature of the Earth as it get warmer.
