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Air! It's all around us:

PISCES Mini-Lesson, Day 2: Air

Pictures of air with different clouds and concentrations of water vapor.

As we said yesterday, the environment is the “ensemble of everything that surrounds us” but, since that's pretty broad, let's look at some of the components individually, starting with air!

Air is pretty important, seeing as how it's what we breathe and all. Interestingly though, the oxygen that we breathe only composes 21 percent of the air. We can, and should, thank oceanic plankton, trees, and plants for converting the carbon dioxide that we exhale back into oxygen so that we have a ready supply of oxygen to keep on living.

Molecular Nitrogen (two nitrogen molecules tightly bound to each other) makes up the vast majority of air (78 percent) and is inert, meaning it's just doing it's thing and doesn't react with anything. Nitrogen is incredibly important for plant growth because it's needed to make chlorophyll, which is what plants use to convert sunlight to food and lets them grow and be all green. Seeing as how nitrogen is all around us in the air, you'd think that plants would be able to get the Nitrogen they need without breaking a sweat. But in reality it's more like one of those “Water, water everywhere, but not a drop to drink” situations. Since the nitrogen in the air is generally inert, it takes a special kind of bacteria to “fix” or convert atmospheric nitrogen to organic nitrogen which other plants and organisms can then use. While plenty of nitrogen-fixing bacteria live solo in the soil, others are associated with nitrogen-fixing plants or trees, such as beans and peas. These plants play a vital role in maintaining healthy soils that allow ecosystems to flourish.

The remaining one percent of air is composed of trace elements, nine-tenths of which is the noble gas, argon. Interestingly, Carbon Dioxide which has gotten a lot of attention as the most abundant Greenhouse Gas makes up only 0.04% of the atmosphere, but it is still exerting a disproportionate effect on the earth's climate.

Water vapor is also present in varying quantities depending upon the temperature, humidity, and pressure, which is a good thing since it brings the rain that sustains most human agriculture and civilization!

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