How does altitude affect the density of air?

Question

And don't say because the air is thinner the higher you go up, i already know that. I need to know why it's DENSITY decreases or i'm going to get a C on my homework grade.

Answer 1

Higher altitude results in lower air density. The density of air is due mainly to its own weight. The lower you are in the atmosphere, the greater the weight of air that is pressing down on you from above. That pressure compresses the air at the bottom of the "pile", making it more dense. Higher in the atmosphere there is less air pressing down, and the air therefore expands, becoming less dense.

It's similar to the increase in water pressure as you go down into the ocean. Except that the water doesn't become more dense, since liquids cannot be compressed. But gasses can be compressed, hence the higher air density closer to the earth's surface.

Answer 2

Higher the altitude, lower the density.
As altitude increases, air becomes thinner or less dense. There's addition of water vapor to air that makes the air humid. This reduces the density of the air.

According to the ideal gas law, a cubic meter of air around you has a certain number of molecules in it, and each of those molecules has a certain weight.

Most of the air is made up of nitrogen molecules N2 with a somewhat lesser amount of oxygen O2 molecules, and then other molecules such as water vapor.

Since density is weight divided by volume, we need to consider the weight of each of the molecules in the air. As Nitrogen has an atomic weight of 14, an N2 molecule has a weight of 28. As the atomic weight of oxygen is 16, an O2 molecule has a weight of 32. The molecular mass of air is around 29.

Now, consider a water molecule, H2O. Hydrogen has an atomic weight of 1. Thus, the molecular mass of water is 18. Notice that a water molecule weighs lighter than a nitrogen molecule, an oxygen molecule, and air.

Therefore, when a given volume of air, which contains only a certain number of molecules, has some water molecules in it, it will weigh less than the same volume of air without any water molecules.

For any gas, at a given temperature and pressure, the number of molecules present is constant for a particular volume. As a result, when water molecules (vapor) are introduced to the air, the number of air molcules must reduce by the same number in a given volume, without the pressure or temperature increasing. As the mass per unit volume of the gas decreases, therefore the density reduces.

Also, density depends on temperature and pressure. As altitude increases, the density drops. This is because the density of air is directly proportional to the pressure and inversely proportional to temperature. The higher the altitude, the lower the pressure, and hence lower the density.

Answer 3

easily, water isn't lighter than air, that's heavier than air. Water VAPOR is lighter than air, so humid air is lighter than drier air. The dew factor isn't seen in airplane overall performance, that's in the METAR so that's desperate how close the temp./dew factor unfold is and subsequently how close it would be earlier you get saturation. Dew factor and relative humidity are appropriate. greater humidity makes for a a ways better density altitude, yet temperature has a lots larger impression on density altitude. Dew factor is measured in levels of temperature. it somewhat is the temperature to which the present air would would desire to be diminished to alter into saturated... to be maintaining each and all the water it could carry. The extra beneficial the temperature/dew factor unfold, the fewer the quantity of water in the air whilst in comparison with how lots it would desire to hold. because of the fact the relative humidity is going up, the temperature/dew factor unfold decreases. it somewhat is significant in predicting the quantity of precipitation that would desire to be produced by utilising a climate device. it somewhat is what's can impression your airplane’s overall performance; rain, freezing rain, frost, snow, sleet and airframe icing.

Answer 4

teh density decreases becuase as you go up into the atomosphere the tempurater is colder.. the air molecules are closer togheter..... say sutmihgn about the molecules being farther apart(warm air) or father apart(cold air)

Answer 5

It thins the air out.

Answer 6

also gravity plays a role in this.....