Air Density: Definition and Factors Affecting It

Air density or air density is strongly influenced by several factors. Each of these will be explained in detail in the following articles.

Density or density can be briefly interpreted as a measure of the ratio between the mass of an object and its volume. Density is a measurement of the mass per unit volume of an object. The higher the density of an object, the greater the mass of each volume.

The average density of each object is the total mass divided by the total volume. An object that has a higher density (eg iron) will have a lower volume than an object of the same mass that has a lower density (eg water).

Density has three categories, namely solid, liquid, and gas. All three of course have different concepts, including those related to factors that affect the size of the density of a substance.

What Is Air?

Air refers to the mixture of gases found on the surface of the earth. Air is invisible to the eye, has no smell, and has no taste. The presence of air can only be seen from the presence of wind moving objects. Air is one type of natural resource because it has many functions for living things.

The elemental content of gaseous compounds and particles in the air will vary with the height above the ground. Likewise, its mass will decrease with height. The closer to the troposphere, the thinner the air, so that it passes the limit of Earth’s gravity, the air will be completely empty.

When living things breathe, the oxygen content decreases, while the carbon dioxide content increases. When plants undergo photosynthesis, oxygen is released again.

Air consists of three main elements, namely dry air, water vapor, and aerosols. Dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide and other gases consisting of neon, helium, methane, krypton, hydrogen, xenon, ozone. , radons. Water vapor present in the air comes from evaporation (evaporation) in the sea, rivers, lakes and other watery places. Aerosols are small objects, such as salt, carbon, sulfate, nitrate, potassium, calcium, and particles from volcanoes.

Air Type

If an air mass stays for several days above a certain area, eventually the air in question will acquire special characteristics that apply to that area of ​​the earth’s surface. If, for example, the area in question is hot and humid, the air mass will also be hot and humid. Conversely, if the area in question is cold and dry, the air will also be cold and dry. An air mass that has acquired special characteristics that apply to areas of the earth’s surface that have been experienced for so long is called a type of air.

The definition of a type of air is an air mass that is millions of kilometers 2 and at least 1 kilometer thick. Air has the same physical properties for each horizontal slice. In this case, what is meant by physical properties is humidity and temperature.

The surface area of ​​the earth can be in the form of a type of air called the source area of ​​the type of air, but not every area of ​​the surface of the earth can function as a source area of ​​the type of air. To be able to function as a source area for air types, the surface area of ​​the earth in question must meet two conditions, namely:

  1. The area in question must be very large, so that an air mass measuring millions of kilometers 2 can be above the area for several days.
  2. The area in question must have a homogeneous surface, for example a very wide desert or a very wide snowfield.

Distribution of Air Types

Geographically, air types can be divided into four groups, namely:

  1. Equatorial air type, namely the type of air that is formed in the area around the equator between latitude 20° south and latitude 20° north.
  2. Tropical air type, namely the type of air that is formed in sub-tropical areas between latitudes 20° U/S and 50° U/S.
  3. Polaris air type, namely the type of air that is formed in temperate areas between latitudes 50° U/S and 70° U/S4.
  4. Arctric air type, namely the type of air that is formed in the polar regions between latitude 70° U/S and latitude 90° US.

After being formed, the air type does not stay forever above the air type source area, but eventually the air type will leave the air type source area, and shift to other areas. In its journey, outside the area of ​​origin of the type of air, the type of air in question will pass through areas whose surface properties are different from those of the area of ​​origin, so that the type of air undergoes a transformation (change in properties).

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The longer the time that elapses after the type of air in question leaves its source area, the greater the change in physical properties experienced by the type of air in question, making it more difficult to find out where the type of air came from.

The age of a type of air is calculated from the moment the type of air in question leaves the air type source area. The longer the age of a type of air, the more difficult it is to recognize the origin of the type of air in question.

Definition of Air Density

In physics, it is known that there is a measurement regarding the ratio between the mass of an object and its volume or commonly referred to as density. The basis for this measurement is none other than the difference in density between objects, be it gas, liquid or solid. Can be interpreted as a measurement of air density per unit volume, air density has different density levels.

These differences are usually influenced by several main factors, namely humidity levels and temperature. The higher the temperature or humidity of an object, will affect the increase in the density of the substance, and vice versa. However, this does not apply to all objects, especially for the density of air including the density of florida.

The density of air can be interpreted as a measure of the ratio between the mass of an object and its volume. Having three types, namely solid, liquid, and gas, all three of course have different concepts, including those related to factors that affect the size of the density of a substance. In physics, it is known that there is a measurement regarding the ratio between the mass of an object and its volume or commonly referred to as density.

The basis for this measurement is none other than the difference in density between objects, whether gas, liquid or solid. Can be interpreted as a measurement of air density per unit volume, air density has different density levels. These differences are usually influenced by several main factors, namely humidity levels and temperature and air pressure.

The higher the temperature or humidity of an object, will affect the increase in the density of the substance, and vice versa. Air pressure is strongly influenced by air density (air mass density) or density level. The amount of air pressure depends on the amount of air above it. When the air is at its highest point, there is less air above it. This is what causes the air pressure at high altitudes to be small. Inversely proportional to in the lowlands.

In addition, air pressure is affected by air temperature. When the air temperature is high, the air molecules will expand and the air volume will get bigger. When the volume in the air above a fixed place, the total air mass will decrease, the weight will also decrease, thus affecting the air pressure that occurs.

The formula used to calculate the density of air is:

𝞺 = density of air (kg/m 3 )
𝒑 = air pressure (hPa)

R specific = specific gas constant (J/kg·K)

T = temperature (K)

It should be noted that the density of air is very different from that of solids. Wood or iron have basically the same density. However, air cannot be equated with any substance. The higher the air above sea level, the smaller the density of the air. This is due to the decreasing gravitational force with altitude . The force of gravity will be smaller as the height is getting up. Therefore, the amount of air that is drawn will also decrease.

Compared to mountain peaks, the amount of air around sea level is indeed more. In a room that has the same volume, the air mass around the sea is larger. So the density of air that is owned is also greater. Unlike the air around the top of the mountain, the mass is smaller. This is what causes the density of air around the top of the mountain is also smaller.

In essence, the farther you are from sea level, the smaller the density of fluid or air. Air is basically made up of separate molecules or atoms, so it can move easily. This is what directly makes the force of gravity affect the amount of air in an area.

So why can hot air balloons fly so high? Hot air balloons can expand into the air because they have a density that is smaller than the density of the air around them. The principle is the same as inflating a balloon. When blowing using the mouth, the balloon will not be able to fly. However, when inflated with helium gas, the balloon can fly. This is because the air coming from the mouth is carbon dioxide which has a density of 1.98 kg/m 3 , which is heavier than the density in the air, while helium only has a density of 0.18 kg/m 3 . Air itself has a density of 1.2 kg/m 3.

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Factors Affecting Air Density

After listening to the basic concept of air density. Next, you will be invited to understand a number of things that affect the density of the air. There are at least four things that distinguish it from other types of mass.

1. Comparison of Air at the Top of the Mountain with Sea Level

For those of you who are currently studying physics material, of course you understand very well the concept of the difference in air density when at sea level and on a mountain. Influenced by volume and gravity factors, the amount of air that fills the sea surface is higher than the area around the mountain. This results in a higher density of air at sea level, because it is in a room that has the same volume. In conclusion, the farther from sea level, the lower the density of air or fluid.

2. The difference between Air and Solids

Cannot be equated with the density of solids. For air there are some special considerations when determining its density. If wood and iron can be equated in density because it is a solid object. The basic air determination must be adjusted to the gravitational pressure that exists on earth. As you already know that the higher, the lower the gravitational force. This affects the density of the air because the level of withdrawal is getting lower.

3. Relationship between Air Balloons and Air Density

Have you ever blown up a balloon before? What happened? Can the balloon fly after you blow it up? Of course the answer is no. However, it will be a different story if you fill the air with helium gas like the hot air balloon concept.

If so, the balloon will be easy to fly through the air. This is none other than because the density of the balloon (helium gas) is lower than the density of air, so that the balloon can fly, whether it’s an ordinary balloon or a hot air balloon. However, when you blow it directly from your mouth, the gas that comes out is carbon dioxide which has a higher density than air. That’s why it’s difficult for balloons to fly to fill the air in the room.

4. Air is made up of separate molecules

Did you know that air is made up of a collection of separate atoms or molecules? This is what facilitates the movement of air to fill the room. In addition, it also causes air to have different pressures, especially when faced with high and low gravitational forces. In other words, the force of gravity affects how much air there is in an area.

How to Measure Air Density

After you know the basic concept of the air density. Next, you also have to understand how to measure the density of the air. There is a tool that can be used to measure the density of gas directly, namely the density meter. However, if you want an indirect measurement, you can use a special glass ball that functions to weigh gas or a modified syringe syringe.

The steps that you can follow will be explained in detail below.

  • You can prepare a vacuum chamber with a siring already filled with a certain volume.
  • Please weigh the siring which has a vacuum chamber to find out its mass.
  • Next, in the vacuum or empty space, fill in the type of gas whose density will be measured.
  • Weigh the siring again which has been filled with certain gas substances.
  • Calculate the mass of gas by subtracting the weight before and after the siring is filled with a certain type of gas.
  • As for knowing the volume of gas, calculate the volume of the vacuum that is in the siring.

Based on the method mentioned above, an explanation of how to calculate the density of air can be described in the following example. For example, a gas with the type of helium has a volume of 100 ml and a mass of 0.017 grams. What is the total density of the gas? Using the formula ρ = m/v, the density results are 0.00012 g/ml or if it is simplified to 1.2 g/liter.

So, that’s a brief explanation of the definition of air density and the factors that influence it. Hopefully this variety of information regarding the concept of air density can add to your knowledge base. Other things that are still relevant, please learn from the same site. Hope it is useful.

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