How Does Air Density Change With Altitude

The density of air varies with pressure (the Ideal Gas Police) and the altitude above bounding main level. Mean accented pressure at body of water level is approximately 760 mmHg (101.325 kPa, kN/thou²) with a variation is about +/- 5%.

Altitude and Air Pressure

The air barometer force per unit area varies with altitude every bit shown in the table below:

Distance (grand)	Pressure
	(mmHg)	(kPa)
0	760	101.3
75	753	100.4
150	746	99.5
250	739	98.five
300	733	97.7
450	719	95.nine
600	706	94.1
750	693	92.iv
900	681	90.viii
1000	668	89.one
1200	656	87.5
1350	644	85.ix
1500	632	84.3
1800	609	81.2
2100	586	78.1
2400	564	75.2

Distance and Air Density

Air density and specific volume equally functions of distance above body of water level can be indicated as in the diagrams below:

STP - Standard Temperature and Pressure

• STP - Standard Temperature and Pressure is 273.15 1000 (0 °C, 32 °F) and absolute pressure exactly ten^five Pa (100 kPa, one bar) - according IUPAC - International Wedlock of Pure and Applied Chemistry - since 1982

NTP - Normal Temperature and Pressure

• NTP - Normal Temperature and Pressure (usually used for testing and documentation of fan capacities) is 293.xv K (20 °C, 68 °F) and absolute pressure 1 atm (101.325 Pa, xiv.696 psi) according NIST - National Institiute of Standards and Technology
  

Note! - other definitions of STP and NTP are widely used.

Altitude and Specific Book Correction

The specific volume of standard air at a certain altitude can be calculated by multiplying with the volume correction factor below

Altitude		Volume Correction Factor
(chiliad)	(ft)
0	0	one.00
480	1600	1.05
990	3300	one.xi
1500	5000	1.17
1980	6600	1.24
2460	8200	one.31
2970	9900	1.39

Altitude and Air Pressure

Altitude		Pressure
feet	metre	inHg	torr	psia	kPa
0	0	29.92	759.97	14.7	101.3
500	152	29.39	746.51	xiv.43	99.4
1000	305	28.86	733.04	14.17	97.six
1500	457	28.34	719.84	13.91	95.8
2000	610	27.82	706.63	13.66	94.i
2500	762	27.32	693.93	13.41	92.4
3000	914	26.82	681.23	13.17	ninety.7
3500	1067	26.33	668.78	12.93	89.1
4000	1219	25.84	656.34	12.69	87.4
4500	1372	25.37	644.4	12.46	85.8
5000	1524	24.nine	632.46	12.23	84.3
5500	1676	24.44	620.78	12	82.7
6000	1829	23.98	609.09	11.77	81.ane
6500	1981	23.53	597.66	xi.55	79.six
7000	2134	23.09	586.49	11.34	78.1
7500	2286	22.66	575.56	xi.13	76.vii
8000	2438	22.23	564.64	10.91	75.2
8500	2591	21.81	553.97	10.71	73.8
9000	2743	21.39	543.31	10.v	72.3
9500	2896	xx.98	532.89	10.3	71.0
10000	3048	20.58	522.73	x.1	69.6
10500	3200	xx.xix	512.83	ix.91	68.3
11000	3353	19.viii	502.92	9.72	67.0
11500	3505	nineteen.41	493.01	9.53	65.7
12000	3658	19.03	483.36	9.34	64.iv
12500	3810	18.66	473.96	9.16	63.1
13000	3962	eighteen.three	464.82	8.99	61.nine
13500	4115	17.94	455.68	8.81	lx.7
14000	4267	17.58	446.53	8.63	59.five
14500	4420	17.24	437.9	viii.46	58.three
15000	4572	16.89	429.01	8.29	57.1
15500	4724	xvi.56	420.62	8.13	56.0
16000	4877	16.22	411.99	7.96	54.8
16500	5029	15.9	403.86	7.81	53.8
17000	5182	fifteen.58	395.73	seven.65	52.7
17500	5334	fifteen.26	387.6	vii.47	51.5
18000	5486	14.95	379.73	seven.34	50.half dozen
18500	5639	xiv.65	372.11	7.19	49.5
19000	5791	14.35	364.49	7.05	48.6
19500	5944	xiv.05	356.87	6.9	47.5
20000	6096	thirteen.76	349.5	six.76	46.6
20500	6248	thirteen.48	342.39	vi.62	45.6
21000	6401	thirteen.2	335.28	vi.48	44.vi
21500	6553	12.92	328.17	6.34	43.7
22000	6706	12.65	321.31	6.21	42.8
22500	6858	12.38	314.45	6.08	41.9
23000	7010	12.12	307.85	v.95	41.0
23500	7163	11.86	301.24	5.82	40.1
24000	7315	11.61	294.89	5.7	39.iii
24500	7468	xi.36	288.54	5.58	38.4
25000	7620	11.12	282.45	5.46	37.half-dozen
25500	7772	ten.88	276.35	5.34	36.8
26000	7925	10.64	270.26	v.22	36.0
26500	8077	10.41	264.41	5.11	35.2
27000	8230	10.18	258.57	five	34.five
27500	8382	9.96	252.98	4.89	33.vii
28000	8534	nine.74	247.four	4.78	32.ix
28500	8687	9.53	242.06	4.68	32.two
29000	8839	ix.31	236.47	4.57	31.5
29500	8992	nine.eleven	231.39	four.47	30.8
30000	9144	eight.ix	226.06	4.37	thirty.1

Temperature vs. Elevation Density Correction

The chart above can be used to estimate "temperature vs. elevation density correction gene". The density at a given temperature and elevation can then be calculated every bit

ρ = ρ_ref / f                               (i)

where

ρ = density at the given temperature and meridian (lb_m/ft³)

ρ_ref = density reference at elevation 0 ft and temperature 70 ^oF  - (0.075 lb_m/ft³)

f = correction factor from the chart above

Instance - Density at Elevation 4000 ft and Temperature 300 ^oF

From the chart to a higher place - at top 4000 ft and temperature 300 ^oF the correction cistron is approximate 1.7. The density tin exist calculated as

ρ = (0.075 lb_m/ftⁱⁱⁱ ) / 1.vii

   = 0.043 lb_m/ft³

Source: https://www.engineeringtoolbox.com/air-altitude-density-volume-d_195.html

Posted by: hardinghort1989.blogspot.com

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