Secrets of Air

        Air is one of the most mundane substances around us. It is colorless, odorless and amorphous, yet everywhere – we cannot escape from it. On the small scale, air consists of multiple types of molecules, some of which are crucial for the organisms on earth; while on the large scale, air forms the atmosphere of earth, which essentially is the reason why lives can exist on earth. Today, let’s look at air from different prospective and on the way unfold some secrets of air that you may not know.

1. 21, 78, 3, 3, 94

        If you have taken some high school chemistry, this array of numbers may look familiar to you – at least for me, I used this recipe to cram for my chemistry exams. This array stands for the proportions of each kind of gases that consists air. A common mistake that the general public may make is that, air is made of “air molecules”. In fact, the commonly used term, air, refers to a collection of gases including oxygen (denoted by O2), nitrogen (N2), carbon dioxide (CO2), argon (Ar), and some other kind of gases. By volume, air contains approximately 21% oxygen, 78% nitrogen, 0.03% carbon dioxide, 0.03% other gases, and 0.94% noble gases, of which primarily is argon.

2. The weight you cannot bear

        Air seems to be weightless. The situation does not usually happen where you have to make tremendous efforts to just stand up because the air on your shoulders is too heavy. However, air does have weight, and it IS heavy. Let’s verify this argument through some simple math. The air pressure, defined by the force exerted on a unit area, is about 105 Newton per square meter. The area of your shoulders is about 15 cm * 40 cm = 6 *10-3 m­­2. This gives the force on your shoulder by air, F = 6 *10-3 * 105 = 600 Newton = 135 pounds! Well, apparently you do not feel this weight every time you stand up (in addition to your own weight, of course), so how come? The magic spell is that, air is everywhere! This is saying that, while there is 135 pounds of force on your shoulder, there is also the same amount of force from below that “lifts” you, as long as there is air that you “stand on”. Therefore, you should now understand why the suction cup can “stick” your GPS receiver on your wind shield – there is practically no air in the suction cup, so the atmospheric air pressure keeps it there.

3. Refund!!! There is “water” in my bottle of compressed air!

         Some of you may have used compressed air to blow off the dust on your laptop. When you shake the bottle, you will typically hear the sound of “water” pounding on the interior of the bottle. Why there is “water” in the bottle? In fact, the “water” is actually air! Air does not necessarily have to be in the gaseous state, and it can change from a gas to a liquid or even to a solid when you, for example, compress it to a very high pressure. In this case, the pressure forces the molecules to stay closer to each other, and air appears to be a liquid. (Actually, this is the ultimate difference between a liquid and a gas – the molecule spacing.) In practice, this is how people usually store gases – in a steel, high-pressure bearing tank – so that it would be volume efficient.

4. Wind – a troublemaker but also a blessing

        When there is a pressure difference of air between two regions, maybe caused by the different temperatures, air will flow from the high pressure region to the low pressure region. This process creates one of the most common natural phenomena – wind. In a hot summer day, a breeze is almost bliss. However, you do not want the wind to blow too hard; too fast the wind might be detrimental. Tornado is a wind of this kind. Wind is also one of the reasons that accounts for a phenomenon called ocean current. Ocean current is a continuous, directed movement of seawater. The constant winds in the high seas (far away from shore) direct the surface sea water to move along with the winds due to friction, so ocean current forms. Ocean current is a very important phenomenon – it is a dominant factor in determining the climate of many regions! The most striking example is the Gulf Stream, an ocean current originates at the tip of Florida and extends towards Europe. The consequence is that, due to the Gulf Stream, northwest Europe is actually much more temperate than any other region at the same latitude. The famous Peruvian anchoveta fishery is also a result of ocean current, where ocean current brings abundant nutrition to the area.

5. Epilogue

        Although air is so unnoticeable, it affects our lives in nearly every aspect, either directly or indirectly, just as its universal presence. It protects all the organisms on earth surface from serious cosmic radiation, and retains heat on earth so that the temperature on earth surface would not vary dramatically. I would like to end our investigation of air with a question: air is an important industrial raw material. What is air making?

This entry was posted in Science of Everyday Things by marz2012. Bookmark the permalink.

About marz2012

Greetings from Ruizhe Ma! I am a senior Physics student at DePauw University, IN. My name is most commonly read as ruiz-he and roo-Zee, but it is actually pronounced Ray-Je! Or if you do not bother, Richard is fine. I am from Beijing, capital of China. I came to the U.S. in 2008 after I graduated from high school, and I am a member of DePauw’s honors program Science Research Fellows. As a Physics student, I have engaged in many science research projects throughout my college education, such as studying light pollution in the county I lived, testing cosmic radiation with ballooning systems, and developing an archive system for the Advanced Photon Source at Argonne National Laboratory. For future plans, I intend to pursue a PhD degree in mechanical engineering and continue my career as an engineer/scientist!

3 thoughts on “Secrets of Air

  1. Hey, thanks for that post, it is really rare that we actually think about air and how much it does for us. It definitely fits with the theme where we don’t really notice something that we are so used to. This post actually took me back to my first Biology class at DePauw where we discussed how our atmosphere has changed over time and how that has left some traces in the organisms we see now. We all know that green plants convert carbon dioxide into oxygen and we are very thankful for that because we are breathing that oxygen. Plants do that in order to synthesize their own food, but that machinery they have in order to do the conversion is a special enzyme called Rubisco:
    The interesting thing about Rubisco is that it is an extremely inefficient enzyme! Because of the shape of this enzyme, it can fit both carbon dioxide and oxygen in it’s active site (the place where all the action happens), but it can only work when carbon dioxide is in that spot. This means that the two molecules compete for the spot. From the ratios that you showed we can see that oxygen 21% beats carbon dioxide 0.03% by a lot! This means that only in the small occasion that carbon dioxide is found in the enzyme, then the plant can convert that molecule to oxygen.
    Well in the time when Rubisco was created, all plants were in an atmosphere where the carbon dioxide was the predominant component of “air”, so they didn’t really have to worry about it competing with oxygen for the spot in the enzyme.
    Why has it not changed?
    I guess it’s efficient enough to allow the plants to get enough nutrients to survive, so there is no need to develop a new system. That being said, a plant that undergoes a mutation allowing it to not bind oxygen, but just carbon dioxide in it’s active site would definitely have a leg up in competing and producing it’s own food.
    Thanks for the post, it definitely got me thinking.


  2. Just as Richard pointed out there are many secrets in the air. These secrets are not all good however, the secrets of air are also composed of dangerous ones. One of the biggest dangers of air is secondhand smoke. This danger is so big and can cause such harm to people that many states and restaurants have a no smoking ban for their customers.

    As defined by the Mayo Clinic, secondhand smoke is “also known as environmental tobacco smoke. This includes the smoke a smoker exhales and the smoke that comes directly from the burning tobacco product.” Secondhand smoke mixes with the air and introduces thousands of toxic chemicals. These chemicals include: Benzene, carbon monoxide, chromium, cyanide, formaldehyde, lead, nickel, and polonium. These toxins can linger in the air for hours and can often be smelt on your clothes and in your hair.
    The dangers of smoking are well known and studied, as are the dangers associated with secondhand smoke, but there is an aspect of secondhand smoke that is not included with smoking. The choice. It is often times not the person’s choice to be around secondhand smoke, especially children. Secondhand smoke can be just as dangerous with it causing asthma, cardiovascular disease, and cancer.
    Secondhand smoke is not the only danger that can exist in the air. There is also air pollution. I would say that secondhand smoke could fall in under air pollution but obviously not all air pollution is secondhand smoke. A review article by US News tells that recent research has shown that even low levels of air pollution can cause serious health defects. According to the American Lung Association report, air particular pollution “refers to a mix of solid and liquid particles in the air that can come from natural sources such as dust storms or wild fires, or from such human activities as the burning of fossil fuels in factories or the use of diesel engines”. Short-term adverse effects consist of coughing, wheezing, cardiac arrhythmias, and even heart attacks. The long term come with even more drastic consequences such as asthma, slow normal lung growth, damage lung airways, and an increased risk of lung cancer.
    So you might be asking yourself with the secrets of air highlighting the need and use of air how can one protect themselves from these dangers? Dr. Mittleman, a cardiologist at Harvard University explains that this is not easy. Air is everywhere! He does not recommend a mask saying that most particles can still slip through. I would recommend being smart about the issue, test the air quality in your home, stay away from busy streets or dirty environments, and do not start smoking. Being aware that these concerns exist is the first step to confronting the issue. Air is so important to our everyday lives that we must work to keep it clean.

    Mayo Clinic Secondhand Smoke: Avoid dangers in the air, 2010

    American Lung Association Report,

    US News Health Article, The Real Dangers of Air Pollution, 2007

  3. Great job with the post! You did a great job of making something as usual as air seem extremely interesting. When you are walking around you do not really think about the air around you and it is fun to think that there are actually hundreds of pounds of weight pushing on you from all sides. I really liked how you began the post talking about air pressure and the mass of air and then moved into specific examples that the reader can relate to. You really reached out to your audience.

    I know from being a biochemistry major and having taken some physics courses that the ultimate difference between states of matter is the spacing between the molecules, but I had not really thought about it in the context of those compressed air canisters- good thinking. I also really enjoyed how you tied in weather (wind!) and ocean currents. They were good examples for visualizing the greater affects of air pressure differences, and then tying in examples like the fish hatchery really gives the reader perspective on how air and water currents, ultimately caused by air pressure differences, affect the lives of humans- even in a seemingly unrelated way like the anchovy supply.

    I actually did my final SRF internship at the University of TN’s microbiology department and worked on a project in collaboration with a ecologist who focuses on the marine nitrogen cycle. While reading this post it was fun to think about how the ocean currents influence her research and the cycle of essential minerals throughout the oceans. The website for our collaborator’s work is: The work she is doing relates well to the importance of ocean currents to marine life.

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