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. Q

    Courses Upper atmosphere & space physics - expected course difficulty?

    I'm taking this 400 level astrophysics course next semester, and I'm not sure what sort of difficulty level to expect, since I'm unfamiliar with the material. Any ideas? The course listing in the calendar reads: "Basic space plasma pheonema: the Earth’s plasma and field environment; the...
  2. V

    Deriving pressure, density and temperature profile of atmosphere

    Homework Statement Derive the pressure, density and temperature profiles of an adiabatically stratified plane-parallel atmosphere under constant gravitational acceleration g. Assume that the atmosphere consists of an ideal gas of mean molecular weight \mu. Given \mu=14u, g = 9.81m/s^2, z =...
  3. L

    The Mass of Earth's Atmosphere

    Homework Statement The Mass of an Atmosphere: What is the total mass of Earth's atmosphere? You may use the fact that 1 bar is the pressure exerted by about 10,000kg pushing down on a square meter in Earth's gravity. Remember that every square meter of Earth experiences this pressure from the...
  4. P

    Effect of thickness of atmosphere on the incident light on land

    How would the whiteness of snow appear if Earth's atmosphere were several times thicker? I think it would appear red as most of the blue frequency light would be scattered before reaching the Earth and the majority of light being reflected of the snow would be red. Am i right?
  5. R

    Sodium layer of atmosphere & holographic projection

    Hi guys, I recently read some stuff about satellites in space being able to project 3D images on to the sodium layer of our atmosphere about 60 miles above the Earth. Is this possible? Can the sodium layer potentially be used as a giant movie screen for projections? The stuff i read was about...
  6. C

    How Much Does Earth's Atmosphere Weigh?

    Homework Statement above each square ince of the Earth's surface is 14.7 pounds of air. the density of air at sea level is 1.27g/l. the Earth is 7930 miles in diameter and has a mass of 5.98x10^24kg. use this data to determine the mass in kg of the Earth's atmosphere determine the...
  7. J

    Effect of gravity on atmosphere

    My ten year old asked the following question - why doesn't gravity pull the atmosphere all the way down to the surface of the earth?
  8. C

    Falling on a Planet with No Atmosphere: Observing a Thrown Ball

    If I am in free-fall towards Earth or in this case let's use a planet with no atmosphere to get rid of air drag. So I am in free-fall and then I throw a ball up above me. From my point of view the ball would appear to keep going away from me until i hit the ground. Is this correct?
  9. J

    Calculating mass of the atmosphere

    Homework Statement Calculate the total atmospheric mass between 25S and 25N, between the pressure levels 300mb and 200mb. Assume the Earth is a perfect sphere.Homework Equations Radius of the Earth = 6378km 1 degree latitude = 111km volume of cylinder = pi*r^2*h The Attempt at a Solution I...
  10. T

    Calculate pressure of Atmosphere

    Homework Statement Calculate the pressure of the atmosphere (with approximately plane parallel slab ge- ometry) as a function of height z above the ground. Assume the gas in the atmosphere has constant temperature T and that the equation of state is that of an ideal gas, namely...
  11. J

    What Could Cause the Atmosphere to Hold More Water?

    I've read that our atmosphere contains roughly 1% of our global water. I was wondering what, if anything except increased temperatures, could cause the atmosphere to hold more water than that (maybe even considerably more). Any kinda of idea would be great, even ideas that would involve massive...
  12. L

    Velocities of earth's atmosphere, exosphere etc

    Earth's atmosphere at sea level has the same velocity as Earth's solid surface: 465metres/sec. What about at higher heights? E.g. what's the velocity of the (particles of) exosphere?
  13. P

    Stars from outside the atmosphere

    Hi Guys .. I have a question and I hope I get a good and obvious answer PLZ .. How do stars and moon look like from outside the Earth's atmosphere ? If we went out of the atmosphere of the Earth , will we see the stars in the same way as we see them from .. here ? In other words do the...
  14. Z

    Why does CO2 keep keep heat within the atmosphere? (on the molecular level)

    I know I know this isn't really related to molecular biology, but I figured since Biologists have a strong background in ecology in most cases, I'd be able to get more help here than the Earth forums (especially because biologists know a lot of chemistry). Basically I understand that CO2 keeps...
  15. GRB 080319B

    Angular speed of the Earth's atmosphere

    Does the Earth's atmosphere match the angular speed of the Earth (i.e. is it stationary with respect to the Earth's surface, or is it "sliding" over the Earth's surface)? I'm trying to understand if the Coriolis effect that is creating the spiral pattern present in hurricane would be the same...
  16. B

    Magnetic Vehicle: Possibilities on Earth's Atmosphere

    Can we make a car or vehicle that can ride on the Earth's magnetic field here within the Earth's atmosphere?
  17. Y

    When a meteoroid enters the atmosphere

    When a meteoroid enters the atmosphere and becomes a meteor, it burns due to great fraction between the rock and and the air. But how scientists calculate the exact amount of kinetic energy converted to heat due to fricton and how much of this is used to heat up the rock and how much of it is...
  18. E

    Saturation of water vapor in the atmosphere

    So I have a quick question about something I'm a bit confused on. I was under the impression that, unlike liquids, gasses become more saturated in COLDER temperatures, rather than warmer. My geology teacher told us that the WARMER it is in the atmosphere the easier it is for water vapor to...
  19. J

    Carbon dioxide has Eyjafjallajokull pumped into the atmosphere

    How much carbon dioxide has Eyjafjallajokull pumped into the atmosphere during the present eruption, compared to the amount not pumped in by aircraft during the recent "no fly" period in Europe?
  20. E

    The Amount of Human CO2 emissions vs. The Scale of our Atmosphere

    My biology teacher asserted to our class that compared to the vastness of the atmosphere of our earth, the amount of harmful gasses we are emitting is a fraction of a percent and therefore can be dismissed as harmless, and instead we should be worrying about more fragile ecosystems down here on...
  21. C

    Find force (N) of atmosphere on area

    Homework Statement Your eardrum has an area of about 53 mm2. Sounds become painful to your ear when the pressure variations that are involved in sound reach 200 Pa above and below normal air pressure. At this level, called the threshold of pain, how much force is exerted on your eardrum...
  22. B

    Question about atmosphere pressure

    we define the ATM. pressure as the weight of cylinder of air above the Earth with surface area for its base equal 1 m2 referring to this definition how could we illustrate the pressure at 1- a room with roof . 2- a room without roof . 3- vacuum room.
  23. danihel

    Moon's Lack of Atmos. vs Titan's Abundance

    hello, how come moon is too small to hold any atmosphere and titan has so much atmosphere?
  24. B

    Energy transfer mechanisms within the Earth’s atmosphere

    Help Asap :( Hi I was wondering if anyone could explain this question to me in more simple terms? And what I need to look for? It's confused me :( You are required to summarise the main energy transfer mechanisms within the Earth’s atmosphere, and most importantly to describe the effects of...
  25. F

    Atmosphere lowers total radiation Earth receives

    I was doing some research today and realized a somewhat silly fact. It appears that Earth's atmosphere actually lowers the total amount of radiation Earth's surface absorbs, even though it raises the mean temperature. This should not sound impossible, the atmosphere provides [by re-radiation]...
  26. S

    Calculate the volume charge density of the atmosphere

    Homework Statement In the atmosphere and at an altitude of 250 m, you measure the electric field to be 150 N/C directed downward, and you measure the electric field to be 170N/C directed downward at an altitude of 400 m. Calculate the volume charge density of the atmosphere in the region...
  27. S

    Solving Atmosphere Layers: Deriving Equations for Venus Surface & Atmos. Temp.

    1. Homework Statement Consider a one layer atmosphere for the planet Venus. 19% of incoming solar radiation is absorbed by the atmosphere. 99% of the outgoing radiation is absorbed by the atmosphere. The incoming radiation, E, as measured by satellite is 615 Wm-2. 1) Derive two equations...
  28. W

    What is the mass of the Earth's atmosphere?

    Homework Statement What is the total mass of the Earth's atmosphere? The radius of the Earth is 6.4 x 10^6 m, and 1 ATM = 10^5 N/m^2 Homework Equations F=PA=ma The Attempt at a Solution F_{g}=P_{atm}A_{earth}=m_{atm}g m_{atm}=\frac{P_{atm}A_{earth}}{g}=\frac{P_{atm}\pi...
  29. S

    Better explanation of Radiative Transfer in Atmosphere especially with Saturation

    Re: the absorption & re-emission of long-wave radiation in the Earth's atmosphere. I thought it all made sense until I was trying to work out how to explain it better to others! So the Beer-Lambert equation describes the absorption at a given wavelength as exp(-k.z) where k is a constant...
  30. B

    Pressure Variation in Planetary Atmosphere

    1. Show that the variation of pressure with altitude for a planetary atmosphere (assuming constant temperature) is more accurately given by: p = poek(1/r-1/R), where g is taken to vary as 1/r2 (with r being the distance from the centre of the planet), po is the pressure at the surface, R is the...
  31. P

    Atmosphere of earth - why it isnt static?

    Homework Statement here is Earth and here is atmosphere. Why this atmosphere is going around with Earth when it is going around, not stay in one place static? i mean not this motion around sun but this motion which is making day and night, the air and everything else is going around with about...
  32. T

    Concerning the Earth's early atmosphere

    Hello everyone and happy new year! I'll make it quick. Supposing that we could somehow visit the early Earth, could we see the stars or the Sun? Was the atmosphere ever so dense and full of gases that would hide the light of the stars? Thanks in advance.
  33. N

    Opacity of the Earth's atmosphere

    Hi all, Does anyone know of a reliable tabulation of the opacity of the Earth's atmosphere (for example at zenith distance zero) as a function of wavelength from 100nm to 1 micron? Obviously the opacity varies with different conditions but something like a US Standard Atmosphere model would...
  34. A

    Short existence of liquid water on Mars (explanation related to thin atmosphere)

    I understand that liquid water cannot exists on Mars for extended periods of time because: a) The atmosphere is too thin b) Resulting in a lower boiling point water c) Which leads to sublimification of solid ice into gaseous vapour Quite specifically, I would like to understand the...
  35. A

    Pluto's Atmosphere: Estimating Temp

    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...
  36. M

    Can Water Reach 101°C @ 1 Atmosphere?

    To heat water to 101 degrees C at 1 atmosphere? Is there any case when this is possible? Even off the wall lab stuff will suffice. What if water isn't completely pure, like most tap water here in the states? My teacher says it isn't possible but any caveat to prove him wrong would be...
  37. J

    Setting the Atmosphere on Fire?

    Is it possible? As far as I know you'd need energy from a star nucleus greater than the suns to cause any change in the atmosphere, creating heavier gasses right? Could the amount of oxygen in the air going above 30% have any impact other than fires burning longer, or any human combustion...
  38. H

    How to scan the frequency at atmosphere by using PIC

    i want to launch the can size satellite and do some experiment about radiation and frequency.so, how to scan the frequency at atmosphere by using PIC?
  39. C

    Work done by expansion of liquidfied natural gas to atmosphere

    Hi All, Been try at this for a week now and I know I'm missing something. I'm too far out of university to remember how to do it, but just close enough to know that I should remember. Anyway, I have a steel can containing a mixture of liquidfied hydrocarbon gasses...
  40. J

    Geothermal power entering atmosphere?

    Hello, I am hoping someone on here can help me find a source for a science question I have. How much power enters the Earth's atmosphere from the Earth itself [Geothermal power]? I was reading a discussion on another website, where someone was asking about the Global Warming effect of...
  41. L

    Total mass of the earth's atmosphere

    Homework Statement given: atmospheric pressure near the Earth's surfact=100kPa density of the air near the Earth's surfact=1.3kg/m-3 radius of the earth=6400km the best estimate for the total mass of the Earth's atmosphere: 5x1018 kg. how to work out this value?? Homework...
  42. Spinnor

    Nuclear explosion in space x-rays hit atmosphere.

    Suppose we set off a nuclear weapon 400 km above the surface of the Earth. See: http://en.wikipedia.org/wiki/Starfish_Prime When the x-rays hit the atmosphere what gets the greatest velocity boost, electrons or ions? Can we assume the averaged velocity of all boosted particles is in...
  43. Loren Booda

    Imaging horizontally through the atmosphere

    Can a spy satellite see a person through a vertical window, i.e., with line of sight near the horizon?
  44. H

    Can H2O Form Without an Atmosphere?

    Can H2O form without an atmosphere?
  45. S

    Why is Ozone so high in the atmosphere?

    Ozone (O3) has a higher molecular weight than regular O2 gas. According to Gay-Lussacs law, O2[SUB]and O3 should occupy the same volume, and therefore O[SUB]3 will have a higher density. Higher densities sink, so why does ozone stay so high in the atmosphere?
  46. D

    Residence Time of H2S in atmosphere

    Homework Statement Using the table of atmospheric composition and residence time , calculate the rate of input for N2 and H2S. Question 5 answers A)N2: 4.1 x 1015 mol/yr; H2S: 9.6 x 1013 mol/yr B)N2: 1.4 x 1014 mol/yr; H2S: 9.0 x 109 mol/yr C)N2: 4.1 x 1015 mol/yr; H2S: 9.0 x 109...
  47. V

    What is the composition of a gas giant's atmosphere?

    I have a silly question: what do people understand by "the atmosphere of a gas giant" ? Isn't most of the planet "all atmosphere", or how should one picture this ?
  48. S

    The Atmosphere and Earth's Orbit (Probably Easy Q)

    Hi, just wondering about a (probably) easy queation. Was learning about the coriolis effect today and how since the atmosphere is not rigidly connected to the Earth it appears to veer off a northerly/southerly course in a direction depending what hemisphere it occurs in... etc. Basically its...
  49. G

    Power of atmosphere and skyscraper windows?

    Power of atmosphere and skyscraper windows? Hi i was wondering about a question dealing with atmosphere and windows...If you could help me out by understanding somethings id really appreciate it..thanks alot... In a large cities when wind is forced to blow between two rows of skyscrapers...
  50. K

    Adiabatic Atmosphere: Understand Heat Transfer and Cooling

    Disclaimer: English is not my native language. I'll try to do my best, but i could put some inappropriate term somewhere, if so please forgive me and feel free to correct me, the more i learn the best :P Hello guys. I'm new here, but i don't really think that this post could be addressed to...
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