What is Atmosphere: Definition and 404 Discussions

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

    Fluid Statics Problem: Determining pressure change in adiabatic atmosphere

    Homework Statement At ground level in Colorado Springs, Colorado, the atmospheric pressure and temperature are 83.2 kPa and 25 C. Calculate the pressure on Pike’s Peak at an elevation of 2690 m above the city assuming an adiabatic atmosphere. Known Patm = 83200 Pa T0 = 25° C z-z0 = 2690 m...
  2. T

    Reaching the Speed of Light: Effects in Atmosphere & Space

    When or if an object exceeds the speed of light what will the reaction be a) in our atmosphere, b) in space? Thank you in advance Tom F
  3. J

    Why is the air colder in the upper atmosphere?

    Why is the air colder in the upper atmosphere?
  4. Q

    Atmosphere of Steam on Tenebra - Hal Clement's "Close to Critical

    In Hal Clement's classic tale "Close to Critical" the planet Tenebra has an atmospheric pressure of 800 bar, 3 gee surface gravity, 100 hour rotation period and about 380 C surface temperature. The atmosphere is mostly water vapour and it condenses just enough for huge rain drops to form and...
  5. J

    Why is there no atmosphere on moon

    why is there no atmosphere on moon
  6. F

    What would happen if a tube like this were placed in the earths atmosphere?

    Sorry if this is the wrong forum, I wondered if this belonged in one of the astronomy related sections but I don't know much about physics, I've never even taken a physics class. I constantly daydream about random stuff, and I thought up something the other day that was been bothering me...
  7. E

    Is the Earth's Atmosphere Ever Completely Pure?

    Hi, I am not sure if this is the correct section for this question but it seems to involve both physics and chemistry so I will start here. In a recent conversation a friend stated that no substance within the Earth's atmosphere can be 100 percent pure. It needs to be in space or some...
  8. P

    Would an acidic atmosphere remove oxygen from the area it affected?

    Would an acidic "atmosphere" remove oxygen from the area it affected? By that, I mean, if you could make an area of air acidic, would it suck oxygen away from the surroundings?
  9. S

    Can't solve differential equation for atmosphere density

    Hi I'm a third year physics student currently working on my bachelorstage, and I have a differential equation I want to solve, but can't =). Given an planet with an atmosphere so thick relative to the planet radius, that gravitation in the atmosphere cannot be seen as a constant but decreases...
  10. R

    How could you remove all the oxygen from Earth's Atmosphere? Hypothetically

    Hey all, I'm a science thriller author (www.jeremyrobinsononline.com) and I've got a new story idea with a really big problem. Basically, I need to remove all of the oxygen from Earth's atmosphere, preferably fast, but I can adapt to a longer time frame if need be. Now, this is for a novel so...
  11. S

    CO2 Variance in the Atmosphere

    There is an unexplained mystery as to why atmosphere CO2 levels varies long term (geologically) and short term (glacial/interglacial cycle.) Contrary to what is repeated in many blogs the glacial/interglacial cycle changes of about 90ppm to 100 ppm is not due to colder oceans being able to hold...
  12. C

    Pressure & Temperature in Saturns Atmosphere

    Homework Statement At the top of the NH3 clouds in Saturn’s atmosphere, the temperature To = 110 K and the pressure Po is about 0.5 bar = 0.5 atm. Below this level at a radius of ro=60268 km, the atmosphere is convective and the temperature changes with radius at a constant rate of dT/dr =...
  13. A

    Atmosphere as a function of Zenith angle?

    Homework Statement Find x, the distance from your location to space, as a function of the zenith angle. The height at 0 degrees, H, is ~100km. A picture helps more: http://img23.imageshack.us/img23/3630/picture1orr.jpg Homework Equations ? The Attempt at a Solution I've...
  14. S

    Production of C14 in the upper atmosphere

    I'm having some doubts about the standard idea of N14 + energetic Neutron > C14 + Proton. Is it possible that the generation of C14 could be a reverse form of the C14 beta decay to N14, initiated by the relativistic electrons entering the ionosphere in the auroras? An endothermic Electron...
  15. S

    Can the Atmosphere Vortex Engine Generate Enough Power to Sustain a Small City?

    http://www.thestar.com/article/238291 Out of curiosity, in this article it says that a generator can produce on average 200 megawatts, just enough to power a small city. Does anyone know if they meant for a year or for a day?
  16. E

    Thickness of Earth's atmosphere

    Homework Statement Calculate the thickness of Earth's atmosphere. Assume that the pressure and temperature do not vary with height. Make reasonable assumptions for their values.Homework Equations I think this question has to be solve with ideal gas equation which is PV=nRTThe Attempt at a...
  17. W

    Pressure on an object as it rises up into the atmosphere

    how would you find the pressure on an object as it rises up into the atmosphere ex. A child's helium-filled balloon escapes at sea level and 20.0°C. It reaches an altitude of 3330 m, where the temperature is 5.0°C and the pressure only 0.65 atm. What is the ratio of its volume at this altitude...
  18. P

    Ideal gas law problem concerning the exponetial atmosphere: part 4

    [b]1. Homework Statement [/b Estimate the pressure , in atmospheres, at the following locations:Odgen Utah(1430 m above seas level);Leadville colorado(3090 m) Mt. Whithney (4420 m) and various other cities above sea level. (assume that the pressure at sea level is 1 atm.)Homework Equations...
  19. P

    Ideal gas law concerning the exponential atmosphere

    Homework Statement Consider a horizontal slab of air whose thickness(height) is dz. If this slab is at rest, the pressure holding it up from below must balance both the pressure from above and the weight of the slab. Use this fact to find an expression for Dp/dz, the variation of pressure...
  20. B

    How does the 'atmosphere' of the sun affect ligth from stars passing behind it.

    When the sun goes down over the horizon, we can still see the sun because the light of the sun is bent by our atmosphere. I would imagine that if one were outside of our atmosphere on the far side of Earth away from the sun, yet in a path in line with that light they would also see the sun...
  21. N

    Are O2 Levels in the Lower Atmosphere Decreasing?

    Are O2 levels dropping in our atmosphere? I read something a while ago that mentioned allergies are getting worse due to increasing CO2 levels in atmosphere, so I'm guessing O2 levels are dropping as well. I was in the mountains a week ago (out of a valley), and noticed how easier it is to...
  22. wolram

    Exploring the Turbosphere: A Smell-Free Atmosphere

    Turbosphere The turbosphere (or homosphere) is that portion of the atmosphere that is sufficiently well-stirred by atmospheric motion that long-lived gases are well-mixed and do not appreciably separate by weight. Just so long as there are no nasty scents.
  23. V

    Temperature of Pluto's Atmosphere

    Homework Statement In 1988 telescopes viewed Pluto as it crossed in front of a distant star. As the star emerged from behind the planet, light from the star was slightly dimmed as it went through Pluto’s atmosphere. The observations indicated that the atmospheric density at a height of 50 km...
  24. J

    Terminal velocity when falling through the atmosphere

    Dear all, I have been working my way through the Oxford University physics test sample paper http://www.physics.ox.ac.uk/admissions/combined-sample.pdf" and I have come across this question: A sky-diver jumps out of an aeroplane. Which of the following statements is true after she reaches...
  25. K

    What Prevents Air from Flowing Out of Earth's Atmosphere?

    Just out of curiosity, We know that the atmosphere is at a pressure of approximately 101 kPa at the sea level and decreases with height. But in space there is no atmosphere and hence zero pressure; Should that not mean that the air in the atmosphere should flow out into space like in a free...
  26. S

    Why the Moon Has No Atmosphere

    Homework Statement why moon has no atmosphere? Homework Equations The Attempt at a Solution
  27. wolram

    Leaky Atmosphere: Earth's Magnetic Field Driving Oxygen Away

    http://www.sciencedaily.com/releases/2008/08/080828090715.htm ScienceDaily (Aug. 28, 2008) — Oxygen is constantly leaking out of Earth’s atmosphere and into space. Now, ESA’s formation-flying quartet of satellites, Cluster, has discovered the physical mechanism that is driving the escape. It...
  28. Andre

    Cooling of Atmosphere Due to CO2 Emission: A Critical Analysis

    http://www.informaworld.com/smpp/content~content=a788582859~db=all G. V. CHILINGAR, L. F. KHILYUK, and O. G. SOROKHTIN, 2008, Cooling of Atmosphere Due to CO2 Emission, Energy Sources, Part A, 30:1–9, 2008 ISSN: 1556-7036 print/1556-7230 online DOI: 10.1080/15567030701568727 Heads...
  29. A

    "Possible Life on Mars? Traces of Ammonia Discovered in Atmosphere"

    Researchers think they have found traces of ammonia in Mars' athmosphere. Since ammonia is degraded quickly there, if this were true, it would mean the presence of some ammonia-producing source on Mars. THe best bets for that would be either active volcanoes or microbes, but since active...
  30. fluidistic

    Question about Jupiter atmosphere

    I know it's not a bright question, but I'd like to know the answer as well. I've read that the high atmosphere of Jupiter contains molecules of Hydrogen (H_2). It is well known that (under Earth atmosphere at least), this gas is highly explosive. I just wonder why the atmosphere of Jupiter...
  31. U

    Why is Venus's atmosphere so hot?

    Is the temperature of Venus's atmosphere due solely (or primarily) to its density? What would happen if the sun's light could be blocked from its surface, would the atmosphere eventually freeze? If so, how long would it take?
  32. E

    Refractive index of Martian atmosphere near surface

    Hi folks, Does anyone have a good reference for the refractive index of the near surface Martian atmosphere? (Or alternatively, the means to estimate it from readily available data!) I'm struggling to think of an equation for which I've got enough of the variables to be of use, (for...
  33. C

    Weight of Earth's Atmosphere: How Much Does It Contribute to Gravity on Earth?

    Greetings, I was thinking about gravity on Earth. From what I know, if you are standing on the Earth's surface, all the mass of the Earth below you will pull you downwards (or more correctly, it warps the space above you which pushes you down snug to the ground). But then I thought about...
  34. L

    Understanding Star Movement in the Presence of an Atmosphere | Physics Homework

    Homework Statement In the absence of an atmosphere, a star moves across the sky from horizon to horizon at a constant speed. how does the star appear to move in the presence of an atmosphere? I would say that in the presence of an atmosphere the star don't move at all because of all the...
  35. T

    Fluorescent colours and the atmosphere

    Hi guys. I'm an anthropologist really, and won't pretend I know the finer points of physics. still, this thing bothers me, and hopefully someone on this forum thinks it's an easy question. I noticed a while back that local crafts in highland cultures - Himalayan and Andean alike! - made use...
  36. T

    Fluorescent colours and the atmosphere

    Hi guys. I'm an anthropologist really, and won't pretend I know the finer points of physics. still, this thing bothers me, and hopefully someone on this forum thinks it's an easy question. I noticed a while back that local crafts in highland cultures - Himalayan and Andean alike! - made use...
  37. T

    Please help me about Process of Clouds, Rain, and Struktur of Atmosphere

    Hai all my friend I have task from my school about Process of Clouds, Rain, and Struktur of Atmosphere when rain fall. i don't have more knowledge about it so please help me Thanks
  38. M

    How Much Force to Equal Earth's Atmospheric Pressure?

    Homework Statement #1. What would have to be the area of a person's foot in order to impact a one Earth Atmosphere pressure? What do you need to ask? Homework Equations Earth Atmoshpere pressure= ? P=Force(Newtons)/Area(m2) The Attempt at a Solution
  39. C

    Optical Physics; Light Entering an Atmosphere

    [SOLVED] Optical Physics; Light Entering an Atmosphere Homework Statement Quoted word for word from the question sheet: A light ray enters the atmosphere of a planet and descends vertically 20.0 km to the surface. The index of refraction where the light enters the atmosphere is 1.000, and it...
  40. Mapes

    Radiative transfer to space affected by atmosphere?

    I'm trying to model radiation losses from a flat surface facing the sky at night. If we ignore radiative absorption/emission in the atmosphere, the heat flux is the well-known Q=\epsilon\sigma(T_s^4-T_\infty^4) where we have the emissivity, the S-B constant, the temperature of the surface...
  41. C

    Scattering in water or atmosphere

    hi, i want to know why scattering can occur when the light beam meet the particle, dust in atmosphere or molecules in water ..., but why not when they meet the glass surface and let the electrons in the glass surface be scattered? can anyone kindly help me, and tell me more about this ? thanks...
  42. K

    Escape Velocity and the Atmosphere

    exiting Earth's atmosphere?? could someone please explain why the shuttle needs such a great velocity to exit our atmoshere? my son would like to know why we could not use a balloon to slowly rise out,I told him that a balloon would pop because of lack of preasure and that got me thinking, if...
  43. O

    What keeps the atmosphere of a planet in place?

    What keeps the atmosphere of a planet in place? THZ
  44. Z

    Oxegen signature of a planet's atmosphere

    Oxygen signature of a planet's atmosphere How far away from Earth might the oxygen signature of our atmosphere be spectographically detectable? The flip side is how far away might an exo-terrestrial planet's atmospheric oxygen signature be detectable? Also then this would be the distance at...
  45. I

    Rocket escaping Earth's atmosphere

    Hey guys, I didn't really know where to put this and this seemed like the most logical place. Also sorry if there's already been a post like this, I tried searching and couldn't find anything. Anyway, onto the question. I'm sort of confused about some things to do with rockets and such. First...
  46. A

    How Does Air Resistance Affect Terminal Velocity and Impact Energy?

    Potential energy: so I guess one form of potential energy would be using mass and gravity and height. Question, in the real world if you take a ball up to 50' and drop it at some point it would reach terminal velocity. Then say you take it up to 2000' and drop it it, it would reach that same...
  47. T

    Atmosphere temperature gradients at altitudes impossible?

    atmosphere temperature gradients at altitudes impossible?? Here's a link to a graph: http://vortex.plymouth.edu/atmosphere/layers.html" I don't understand how this is possible. The atmosphere is Warm at the surface, (due mainly to infrared heat from Earth's' surface -ok) Cold at...
  48. T

    Earth's surface temp without atmosphere vs moon's

    Without an atmosphere, the Earth's average surface temperature would be -18 C. The moon's surface temperature averages -23 C. Is this 5 degree C difference due to heat from the Earth's core? (I'm not a student; I'm curious about the climate debate, and trying to figure some things...
  49. N

    Rayleigh scattering in Earth's atmosphere

    Does anyone know a rough ballpark figure for the opacity of the Earth's atmosphere in the visible? Assuming an observer is at sea level looking to the horizon, I calculated the opacity due to Rayleigh scattering in the visible band, as shown in the attachment. I don't really require a high...
  50. B

    What caused the disappearance of Mars's atmosphere and surface water?

    I hope someone can clear up some issues about Mars's atmosphere, specifically: -- Since most evidence indicates that Mars once had surface water, I assume that it must have had a considerably more substantial atmoshpere than it currently has. --- A magnetic field is necessary for the...
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