Atmospheric Definition and 273 Threads

An atmosphere (from the greek words ἀτμός (atmos), meaning 'vapour', and σφαῖρα (sphaira), meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in place by the gravity of that body. An atmosphere is more likely to be retained if the gravity it is subject to is high and the temperature of the atmosphere is low.
The atmosphere of Earth is composed of nitrogen (about 78%), oxygen (about 21%), argon (about 0.9%), carbon dioxide (0.04%) and other gases in trace amounts. Oxygen is used by most organisms for respiration; nitrogen is fixed by bacteria and lightning to produce ammonia used in the construction of nucleotides and amino acids; and carbon dioxide is used by plants, algae and cyanobacteria for photosynthesis. The atmosphere helps to protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays. The current composition of the Earth's atmosphere is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms.
A stellar atmosphere is the outer region of a star and typically includes the portion above the opaque photosphere. Stars with sufficiently low temperatures may have outer atmospheres with compound molecules.

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  1. K

    Atmospheric pressure to gas pressure in the apparatus

    Homework Statement If the atmospheric pressure is 745 mm Hg, what is the gas pressure in the apparatus in atm? (Hint: the gas pressure is not equal to atmospheric pressure. Which is greater Pgas or Patm?) Be careful with your units, 10.2 cm is equal to 102 mm Homework Equations...
  2. A

    Atmospheric Pressure Above the Sea Level

    Homework Statement The atmospheric pressure deceases exponentially with height. At 5.5 km, the pressure is half that at sea level. At what height is the pressure one eighth that of sea level? Homework Equations All I can think of is Pat=ρgh I know 1 atm=101325 Pa=101.325 kPa and that this is...
  3. A

    Limitations to the practical use of atmospheric electricity?

    "In fine weather, the electric potential increases with altitude at about 30 volts per foot (100 V/m)...." what hinders its practical application as a source of power, as a battery?
  4. C

    Vapor Pressure and Atmospheric Pressure

    From what I have read so far, the vapor pressure of a liquid is temperature dependent while it is independent of the atmospheric pressure. I am not sure why atmospheric pressure would have no effect of the vapor pressure though. For example, if a highly volatile liquid is placed in a sealed...
  5. K

    Short term atmospheric retention.

    What timefram does short term atmospheric retention mean?
  6. M

    Atmospheric Density Profiles of Europa and Mars

    Hi all, This is my first post. I am a fourth year undergrad doing a project on astrobiology. in order to do calculations of meteorite impact on the surfaces of europa, enceladus, and mars, i need their atmospheric density profile models. Any idea where i could find those? thanks in...
  7. C

    Atmospheric Creation on the Moon

    First post, long time lurker. Supposing that mankind were to first choose the Moon as the celestial body for colonisation (no questions at this point, those in favour of Mars pretend for a second it has some sort of life on it!), how would we go about creating a significant atmosphere on the...
  8. leviterande

    Atmospheric pressure & the vacuum of space

    I have a question I long pondered and couldn't find any explanation to exactly what I want. We all know that atmospheric pressure is due tu gravity acting upon everything on earth. this pressure act from all directions on all our body molecules. However in space there is no gravity, no...
  9. Y

    Atmospheric Pressure & Boiling Point of Water: 20 C

    What does the atmospheric pressure have to be to make the boiling point of water 20 C?
  10. V

    Why does liquid co2 goes back to solid at atmospheric press

    I you look at the phase diagram, CO2 is in liquid state at 5,11 atm and t= -56 C. But why does he convert directly to solid state at 1 atm? Again, if you go down from five to one atm, you should be in gaseous state ? Is it have something to do with temperature ? What happens with temperature...
  11. H

    CLIMATE physics-general atmospheric circulation

    Homework Statement I'm trying to find sketches that demonstrate ,the general circulation patterns of the atmosphere and the cells in atmosphere of a planet.3 cases must be considered:a slow rotating ,a fast rotating and a non rotating planet. Homework Equations The Attempt at a...
  12. B

    Torricelli Barometer and atmospheric pressure

    Homework Statement I have a Torricelli barometer column filled with mercury. Situation 1: Temperature1 = 20° C. Height: 0,760 m. Outer pressure:1 atm. Situation 2: Temperature2 = 35° C. Height: 0,762 m. Coefficient of termic dilation in the interval (T1, T2): 18,2 *10^-5 (°C)^-1 Find...
  13. C

    Atmospheric C14 is measured permil Permil of what?

    Atmospheric C14 is measured "permil". Permil of what? I'm interested in understanding how the level of atmospheric radiocarbon has declined since atmospheric nuclear testing ended. Please excuse my ignorance of what is no doubt something extremely elementary. Atmospheric C14 measurements...
  14. A

    Atmospheric Pressure Sounds Intense

    Ok, so 1 atm≈101,300 Pa that is 101,300 Newtons per square meter, presumably at sea level. If we look at the force in terms of lbs this is 101,300 N* (.225 lb/1 N)≈22,792 lb. The pressure per square meter seems pretty intense to me when I thought of it in terms of force. I didn't ask my...
  15. A

    What causes atmospheric pressure: gravity or molecular collisions?

    Hello All, It is said that Earth has an envelope of gases (air) surrounding it and that due to gravity the weight of this envelope of air exerts a force: on the surface of Earth and any thing on it. The weight of air column on any surface divided by the area of the surface is...
  16. P

    Is It Possible to Generate Electricity from Atmospheric Heat?

    While searching net, I recently have come in touch with two very interesting patents. Both applications were patent granted. Both claim to produce electricity by using atmospheric heat. Here they are...
  17. H

    Force from fluctuations in atmospheric pressure

    Say you have a giant mercury barometer. Let's suppose that the area exposed to atmospheric pressure is 1 square meter Normal pressure at sea level is 101325 Pa Lets say the variation in 24 hours in atmospheric pressure goes from a low of 100,000 Pa to a high of 102,000 Pa Using...
  18. V

    Question about Atmospheric pressure

    Homework Statement The problem is this: If T(temperature) AND P(pressure) of air increases, what can we assume about D(density)?Homework Equations Well, I know that as temperature increases, pressure increases and vice versa. When you try this question out with the equation P=KdT it doesn't...
  19. C

    Exploring the Possibility of a Vacuum-based Buoyancy System for Atmospheric Lift

    Hi, first time posting here. I was watching a show about hydrogen/helium balloons and it got me thinking about buoyancy in atmospheric gasses (nitrogen) and what might work better than the common gasses and I considered that since the goal of a balloon is to reduce the internal mass relative to...
  20. O

    Curious Question about Atmospheric Pressure.

    I am new here and I have a question about pressure. My idea about atmospheric pressure is that it is a pressure caused by the force directed downward due to the weight of the atmosphere. If that is the case, does it mean that we doesn't feel any pressure horizontally? Please correct me if I am...
  21. H

    Atmospheric Electic Field: Can It Ever Provide A Reliable Energy Source?

    [I realize and understand that trying to harness storm lightning is fairly impossible/impractical, so that is not the focus here, unless someone has some info contradicting that.] The basic question I have is this: there is a strong altitude correlation in the distribution of positive (higher...
  22. G

    Why multiply atm by atmospheric pressure in pascals?

    Consider the following two-step process. Heat is allowed to flowout of an ideal gas at constant volume so that its pressure dropsfrom PA = 2.7 atmto 1.4 atm. Then the gas expands at constant pressure, from avolume of 6.8 L to VC = 13.1 L where the temperature reaches its originalvalue. See Fig...
  23. E

    Temperature - Effect on atmospheric pressure.

    What is correlation between temperature and atmospheric pressure? For example, why does Titan have 1.6 times the atmospheric pressure of Earth despite having pretty much the same atmospheric 'weight', for lack of better term. (Total atmospheric mass times gravity.) EDIT: Is this the right...
  24. E

    Atmospheric Gases - absorption, reflection, and emission of radiation

    I'm going to be very careful to avoid the word "greenhouse" because of the indefinite ban on discussions about climate change - I want to be clear, this isn't a topic about that. Part 1 - some gasses in the atmosphere absorb and emit radiation in the thermal infrared range. Gases like water...
  25. A

    Atmospheric Surface Pressure and Density

    I am not sure this belongs here. However, I could not think of where else to put it. I am rewriting an old Stellar System Generator originally began way back in 1983. I kept updating and revising it until the death of my family in 1997. I just recently found it in some old file boxes and...
  26. M

    Building an atmospheric chamber

    Building an "atmospheric chamber" I have to build a chamber (ok, large box) to do some atmospheric pressure tests. The box will be 48 inches square. I have to simulate going from sea level (0 feet, 14.696 psia) to 7000 feet (11.34 psia). I'm thinking of building the "box" from 3/4" plywood...
  27. Shackleford

    Is M.S. Atmospheric Science as challenging as a math major with a physics minor?

    Surprise, surprise! Another graduate program I'm considering at my university. I'm wondering how this would compare difficulty-wise to my math major, physics minor. It looks like most of the classes I'd take have Intro. to PDE as a prerequisite, e.g. Atmospheric Physics/Chemistry, etc. For my...
  28. L

    Airplane Wings & Atmospheric Pressure

    1. I got the correct answer but I am confused about the reasoning and want to understand the concept.. "Rank from most to least, the amount of lift on the following airplane wings: a. Area 1000 m^2 with atmospheric pressure difference of 2.0 N/m^2, b. Area 800 m^2 with atmospheric pressure...
  29. Simfish

    Atmospheric Science/Meteorology Resources

    http://www.theweatherprediction.com/ http://stratus.astr.ucl.ac.be/textbook/contents.html (Introduction to Climate Dynamics and Climate Modelling - free online textbook) http://wunderground.com, http://www.weatherspark.com, http://www.wrcc.dri.edu/ => good for historical data for any...
  30. S

    Problems about atmospheric pressur

    Hi, I'm doing some physics exercises but some don't result correct, could you help me? thanks! Homework Statement 1)Calculate the necessary force to open a 0.3 m length square metallic container with a 410 mmHg inside pressure knowing external pressure is 0,980 atm 2)There is a hollow...
  31. B

    Question about atmospheric pressure

    For a given mass, as radius decreases, would atmospheric pressure increase, since surface gravity would increase? I'm assuming that atmospheric composition doesn't change. For a planet with radius = 1.1*Earth and mass = 1.3*Earth and atmospheric molar weight within 1% of Earth's, does a...
  32. T

    Does Atmospheric Viscous Drag Affect Upper Atmosphere Rotation and Air Movement?

    I guess the Earth's surface pulls around the lower atmosphere with viscous drag effects? What about the upper atmosphere? Does it rotate with a slower absolute tangential velocity? If so, is there any pressure difference that caused by the difference in velocities that would cause any...
  33. FtlIsAwesome

    Extraterrestrial sky color based on atmospheric composition and sun color

    How can one determine the color of another planet's sky from its atmosphere composition and parent star color? Earth's atmosphere is blue for most of the day, then turns red at sunset. Mars is sort of the opposite: it has a red sky which turns to a bluish hue at sunset. Until someone tells me...
  34. M

    Atmospheric pressure is always exert on downward direction?

    atmospheric pressure is always exert on downward direction?? atmospheric pressure is always exerted on downward direction...but can i think soo it exerted in horizontal and also atmospheric pressure exerts from downward direction is it true?
  35. H

    Question - Atmospheric Perspective

    Hello! Please excuse me if I posted this in the wrong place. I've never been too good at these forum things, but I did have a question about atmospheric perspective that I believe has more to do with physics than any other category on the forum. While doing a personal artistic study on...
  36. M

    Atmospheric Extinction of Light

    If I have a 2,000 candelas red light source under normal rural atmospheric conditions at what distance would I expect the source to no longer be visible to the eye?
  37. P

    If the atmospheric pressure is 0.975 atm

    Homework Statement If the atmospheric pressure is 0.975 atm, what is the pressure of the enclosed gas when its an open-tube manometer and the h is 52 cm? The Attempt at a Solution I know you would have to set up a proportion. I was thinking .975 / 1 = x / 760 x = 741 torr But...
  38. F

    Atmospheric Scattering: Why We See Sunsets Red/Orange/Yellow

    I don't quite understand why we see sunsets as red/orange/yellow. We see the sky as blue because Rayleigh scattering causes the smaller particles within the atmosphere to scatter bluer wavelengths and absorb others. But if the others are absorbed, which would include the red/orange/yellow...
  39. P

    Pressure due to an elephant and atmospheric pressure

    The pressure exerted against the ground by an elephant's weight distributed evenly over its four feet is less than 1 atmosphere. Why, then, would you be crushed beneath the foot of an elephant, while you're unharmed by the pressure of the atmosphere?
  40. F

    Universities with Top Atmospheric Sciences Programs in the US and Canada

    Hello to everyone...I have just completed my undergraduate studies in Physics and I am thinking of sending applications to Atmospheric Sciences Programs. So I would like to ask if someone knows which Universities ( USA or Canada ) offer a good graduate program and have a good reputation in...
  41. D

    Surface temperature to Atmospheric temp.

    Homework Statement The surface temperature of a city is 20 degrees celsius. What is the temperature at 2 km above the surface if the temperature decreases at "half the average rate" of the troposphere? Show your calculations. Homework Equations None really, it may be just simple math...
  42. K

    Mass difference corresponding to atmospheric oscillations

    Hi, In arXiv:hep-ph/0307149v2, it is mentioned that atmospheric mass-squared difference is not uniquely defined and that the convention that is going to be used is that it is the largest possible mass-squared difference. I know that the smallest mass difference is identified with solar...
  43. O

    Density of Atmospheric Gas Using Newtonian Gravity

    Hello. I've recently been working on the mathematics of atmospheric/stellar density, but I've run into an apparent paradox with the assumptions I have been using. I hope this is the right forum for this question. At the moment, I'm working on the equations for the atmospheric pressure/density...
  44. T

    Question possibly to do with atmospheric pressure (but possibly not)

    I have a question about my watch which has been bugging me for a little while, and I was wondering if anyone could enlighten me as to the physics behind it. One day a while back I went out for a run in the rain and some water got into my watch, behind the glass. I only noticed because it had...
  45. A

    Blood pressure and atmospheric pressure

    The normal atmospheric pressure is 760 mm of Hg. But the normal human blood pressure is around 120/80 mm only. In that case how equilibrium of our body is achieved? For any vessel to retain its original shape its inside pressure and outside pressure should remain equal. If the outside pressure...
  46. A

    Can Powered Atmospheric Re-entry Reduce Heat Shield Dependence?

    This is something I've wondered for some time. Our spaceships need all this ablative heat shielding because they slam into the atmosphere at ludicrous speeds, thereby generating a ton of friction and heat. Wouldn't it make more sense to slow down first? There is an orbit where the speed of the...
  47. F

    Atmospheric pressure 1Atm or 100 kPa?

    Ignoring normal variations, I've always been told that atmospheric pressure is... 1 Atm = 101,325 Pa However, Wikipedia says atmospheric pressure was re-defined in 1999 to be exactly 100 kPa. This would mean that atmospheric pressure is now 0.98692 Atm...
  48. S

    Can One Make the atmospheric pressure to store energy

    If I Make two(many) tanks to fill water each one at different height levels. 1. Fill the lowest tank with water, open it to atmosphere. 2. close the second tank and create vacuum in it. make water flow from first tank to this till it gets filled. will this process allow me to store extra...
  49. S

    Atmospheric Pressure: Why Don't We Feel It?

    why don't we feel the atmospheric pressure although it is large ??
  50. F

    Me here atmospheric chemistry question -:-( got test tom

    please help me here atmospheric chemistry question urgent --:-( got test tom Homework Statement a particle in a cubic box has an energy equal to (2^2+1^2+1^2) XE0 =6E0 where Eo=h^2/8ma^2 what is the degeneracy of this enegry level? this is the Queston Homework Equations The Attempt...
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