As altitude increases how does density change

The air density depends on both the temperature and the pressure through the equation of state and also decreases with increasing altitude. Aerodynamic forces directly depend on the air density. To help rocket designers, it is useful to define a standard atmosphere model of the variation of properties through the atmosphere. There are actually several different models available--a standard or average day, a hot day, a cold day, and a tropical day.

The models are updated every few years to include the latest atmospheric data. The model was developed from atmospheric measurements that were averaged and curve fit to produce the given equations. The model assumes that the pressure and temperature change only with altitude. The particular model shown here was developed in the early sixties, and the curve fits are given for English units. Curve fits are also available in metric units. It increases feet - that's on an average day!

How about Denver, Colorado? Denver International Airport sits at feet, and its average temperature in July is 88 degrees Fahrenheit Since the standard temperature decreases 2 degrees Celsius for every feet, Denver's standard temperature is roughly 4. On an average day in July, Denver's temperature is 27 degrees Celsius above standard!

What does that do to Denver's density altitude? On an average July day, the temperature increases Denver's density altitude by feet to feet! That's why every one of Denver International's runways is at least 12,' long - and one is 16,' long. Did you know that humidity also plays into density altitude? In the atmosphere, Nitrogen usually exists as a N 2 molecule - which means two Nitrogen atoms are bound together.

Since Nitrogen's atomic mass is 7, one Nitrogen molecule weighs 14 units. Oxygen in the atmosphere generally exists as a O 2 molecule, which means two Oxygen atoms are bound together.

Oxygen's atomic mass is 8, so one O 2 molecule weighs 16 units. Water molecules are made up of two Hydrogen atoms, each of which weighs one unit, and one Oxygen atom, which weighs 8 units - so a molecule of water vapor weighs 10 units.

What's with all of the chemistry?!? Water vapor weighs less than the Nitrogen or Oxygen molecules that make up the rest of the air. And, water vapor takes up about the same amount of space. So, when you have more water vapor in the air, the air has less mass - which means it's less dense.

Unfortunately, factoring humidity into density altitude is complicated, but there's a great calculator for it here. These may range from headaches and dizziness to much more serious consequence s, such as brain or lung damage.

Above about 8, meters 26, feet , the human body cannot survive at all, and starts to shut down. Mountaineers call this altitude the "death zone. To prevent severe altitude sickness, mountaineers bring supplemental extra supplies of oxygen and limit their time in the "death zone. Different regions have different air pressures, even at the same altitude.

Factors such as climate and humidity impact local air pressure. Air pressure also decreases around the pole s. For this reason, if Mount Everest was located in the U. In astronomy , altitude has a somewhat different meaning. It describes the angle between the horizon and some point in the sky. For example, if a star is directly overhead, its altitude is 90 degrees. If a star has just set or is just about to rise, it is right at the horizon and has an altitude of 0 degrees. The North Star , Polaris, does not rise or set because the Earth's axis passes directly through it.

It thus has a constant altitude when viewed from anywhere in the Northern Hemisphere. This makes it incredibly useful in celestial navigation. Mount Everest is the highest point of altitude on Earth. Photograph by George F. Northern Hemisphere. North Star. Also called the Lodestar or Pole Star. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.

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