Aviation and Aerodynamics for Schools
Initiative Aviation Base Hamburg: Education
Informations about the Atmosphere
last updated
The atmosphere of our earth does not reach very far into space. From an orbit you see it very distinct just before dawn as a blue stripe above the horizon. Click onto the image to load a hires image of this last Space Shuttle mission (source: NASA 2011). You load a short movie of this here: sunrise_shuttle.mov (source: NASA 2011) |
This image shows a hurricane. But you can see the atmosphere very nicely. (source: NASA). Click onto the image to load a hires image. | Closest to Earth’s surface, the orange-red glow reveals the troposphere—the lowest, densest layer of atmosphere, and the one we live within. A brown transitional layer marks the upper edge of the troposphere, known as the tropopause. A milky white and gray layer rests above that, likely a slice of the stratosphere with perhaps some noctilucent clouds in the mix. The upper reaches of the atmosphere—the mesosphere, thermosphere, and exosphere—fade from shades of blue to the blackness of space. (source: NASA 2011) |
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ISS crosses the Carribean, the US, and the north pole. Load films here, too! Source: NASA 1/2012 |
Moonset over South America, filmed from the ISS (shows the thickness of the atmosphere). |
The standard data of the atmosphere (US standard atmosphere) are:
Pressure p = 101325 Pa = 760 mm Hg
Temperature T = 288.15 K = 15°C
Density rho = 1.225 kg/m3 = 0.001225 g/cm3
Molar Mass M = 28.964 g/mol
Composition of Air in %
Nitrogen | N2 | 78.084 |
Oxigen | O2 | 20.9476 |
Argon | Ar | 00.934 |
Carbon Dioxide | CO2 | 00.0314 |
Neon | Ne | 00.001818 |
Helium | He | 00.000524 |
Krypton | Kr | 00.000114 |
Methane (Natural Gas) | CH4 | 00.0000087 |
Hydrogen | H2 | 00.00005 |
Velocity of Sound in Air depending on Moisture at 20°C (68°F)
344 m/s (343.477 344.742 m/s)
1238,4 km/h (1236.52 1241.07 km/h)
769.5 mph (768.338 771.165 mph)
For dry air as a an ideal gas:
T in °C T in °F v in m/s v in km/h v in mph
-100 |
-148 |
263.5 |
948.6 |
589.4
|
-50 |
-58 |
299.5 |
1078.2 |
670.0
|
20 |
68 |
343.4 |
1236.24 |
768.2
|
40 |
104 |
354.8 |
1277.28 |
793.7
|
80 |
176 |
376.7 |
1356.12 |
842.7
|
Differences in pressure almost do not play any role for the speed of sound.
Viscosity of Air
Temperature and Viscosity in 10-5 poise (µPas)
K |
°C
|
°F
|
µPas
|
100 |
-173
|
-279.67
|
7.1
|
200 |
-73
|
-99.67
|
13.3
|
300 |
27
|
80.33
|
18.6
|
400 |
127
|
260.33
|
23.1
|
500 |
227
|
440.33
|
27.1
|
600 |
327
|
620.33
|
30.8
|