Our atmosphere surrounds Earth’s surface. This atmosphere contains the oxygen we breathe, protects us from harmful ultraviolet rays and causes most meteors to burn-up instead of smash into the surface.
The atmosphere also serves the dual function of being an insulating blanket at night and sunscreen during the day. Without the atmosphere, temperatures at the surface would swing wildly from extremely hot in the day to unbearably cold at night.
The part of the atmosphere in which life can survive (called the troposphere) is only 6-7 miles thick. If the earth were the size of a volleyball, the thickness of the troposphere would amount to about two sheets of copy paper stretched snugly over the volleyball’s surface.
The components of our atmosphere as a whole, when made free of water vapor, are 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon. The remaining 0.1 percent is mostly carbon dioxide.
Water vapor (humidity) varies widely from place to place. In very cold dry areas, the water vapor in the air is almost nothing. However, in very humid areas, water vapor can make up to 5 percent of the actual air.
Two things really intrigue me about the make-up of our atmosphere — and, no, it is not the amount of greenhouse gasses or how they are changing. I’ll let others discuss that.
My first fascination is: Where is the hydrogen and helium? The second question is: Why so much nitrogen?
Hydrogen and helium are the simplest and by far the most abundant elements in the universe.
So, why are these common gases so poorly represented in our atmosphere?
First, these two are the lightest elements, and they did make up the majority of our early atmosphere as the Earth formed in the infant solar system.
These light elements, in time, mostly escaped the Earth and were lost into space.
You know, I just don’t like the idea of anything from Earth being lost into the oblivion of space. It seems to me we need what little of the universe we have here on Earth to stay put.
I must add for the record that a fair amount of that original hydrogen did hook up with oxygen to form the water for our oceans.
As to why the 78 percent nitrogen?
It is a long and complicated story, but the CliffsNotes version is that nitrogen is boring. Nitrogen is extremely stable and reacts with almost nothing.
So, as the original hydrogen and helium skipped out and the original oxygen got to work on water, life and other reactions, the nitrogen mostly sort of stuck around and outlasted the others.
I could go on and discuss barometric pressure, wind, etc., but I won’t here — maybe in another column.
I like to think of our atmosphere as the collective spacesuit for all the living organisms here on earth, not unlike the individual spacesuits worn by our astronauts during spacewalks.