Shirley Boyce age 13, of Adams City, Colorado, for her question:
Where so we get our winter supply of oxygen?
We learn that green leaves use a magic recipe to pour oxygen into the air. And this is true. Oxygen, we knows is the gas we breathe in the gas necessary for us, and for all living things to stay alive, Then, some morning in the fall, we look out to see the green leaves wearing the colors of the rainbow, getting ready to drift to the ground. All the busy little green leaf factories that, among other duties, have been making precious oxygen all summer are getting ready to shut down for the winter.
Naturally we wonder what this is going to do to our supply of oxygen, Is there less oxygen in the air during the winter months? Should we go on short rations and maybe hibernate like the frogs and bears? Andy says this is not necessary, Furthermore, there is no need at all to worry about the supply of breathable oxygen for us and for all living creatures. Year in, year out, summer and wintery there is enough oxygen and to spare for us, for all living things and for all the fires we need to keep us warm and comfortable.
Measurements show that the oxygen content of the atmosphere remains just about the same in all places on the earth and at ail times of the year. A sample of air from the North Pole contains about 20.9 per cent oxygen the same proportion as from a scoop of air at the equator, from the Sahara Desert and from the stately pine forest in Oregon.
That stately pine forest is one thing we forget when we start worrying about our winter supply of oxygen. Millions of acres of evergreen forests on our continent alone never shut down their oxygen factories, winter or summer. Uncounted miles of tropical forests also pour out oxygen summer and winter. The trees of the huge continent of Australia also ignore the seasons and many trees in the southern hemisphere have their summer whilst we are having winter. Their leaves are green and busy giving out oxygen while ours are bare and resting,
No matter where it is made the oxygen from green trees is a world traveler. Like all gases it spreads out to occupy all the space it can get. It rides the winds around the world. A 20 mile¬ an hour wind can shift 100 million tons of air through a square mile in one hour and over 20 per cent of that air is oxygen.
Then maybe because oxygen is so precious to us., we tend to imagine that we need far more of it than we do. Actually, though we breathe in about 20 per cent of oxygen with our airy we only use a little of it. The air we breathe out still contains 16 per cent of oxygen, compared with all the billions of tons in the vast . atmosphere this is little indeed. It is a small amount even when we multiply it by all the breathing creatures and all the oxygen using fires. Our great store house of oxygen in the atmosphere hardly notices it at all.