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. F

    Atmospheric chemistry - how to find a wavelength

    Recently, it has been found that Cl2 can be released to the atmosphere in the marine boundary layer through mechanisms that oxidize chloride (Cl-) in sea salt aerosol. The Cl2 is unreactive at night and can build up to significant levels. Upon sunrise, Cl2 will photolyze, releasing very reactive...
  2. F

    Atmospheric Chemistry, where to start?

    An atmospheric chemist wishes to measure O3 using a portable “ozone sonde” that will be attached to a helium filled balloon. The mylar balloon is non-elastic and has a fixed volume of 2.0 m3 when filled. The mylar balloon has a mass of 500 g when empty. The ozone sonde has a mass of 750 g...
  3. K

    Atmospheric Pressure Problem - Need Help.

    Homework Statement How does the pressure at a point in a fluid vary with the depth of the point below the surface of the fluid? A bottle, full of air at atmospheric pressure, whose volume is 500 cubic centimeters, is sunken mouth downwards below the surface of a pond. How far must it be...
  4. K

    Volume of Air Bubble at Atmospheric Pressure

    Homework Statement My teache recently assigned this problem but its nothing like the atmospheric problems we've done in class. Any suggestions on where to start? The cross section of the tube of a mercury barometer is 1 square centimeter, and when the barometric height is 760 millimeters...
  5. B

    Atmospheric density calculation (of mars)

    Homework Statement gravitational constant G=6.67x10^-11 Nm^2/Kg^2, M=6.42x10^23 Kg, and R=3.40x10^6 m for mars. Calculate the atmospheric density of Mars. Homework Equations Density of water = 1000 Kg/m^3 Atmospheric pressure = 30 Pa (from what I've calculated) p=M/V The Attempt at a...
  6. J

    AIRS and Atmospheric Carbon Dioxide

    http://airs.jpl.nasa.gov/AIRS_CO2_Data/AIRS_and_CO2/" I'm not sure about the long term analysis will work out, but it looks to me like the Atmospheric Infrared Sounder (AIRS) instrument is providing fundamental data about how our climate works.
  7. L

    Atmospheric Pressure in Sealed Water Tank: Fact or Fiction?

    Hello all, i would like to know if atmospheric pressure exists on the surface of water in a completely sealed water tank. So, does atmoshperic pressure exist even on surfaces that are not in contact with the atmosphere, meaning in closed areas above. Thank you.
  8. L

    Atmospheric radiation scattering/absorption

    I am still trying to assess the ability of the sun to heat a house through glass and I am a bit stuck . Most solar flux /radiation measurements I have found are based on a total of direct and diffuse radiation on a horizontal surface and then formulated for vertical surfaces with some cosine...
  9. J

    Solving for ground temperature using atmospheric layer models and energy budgets

    Homework Statement Imagine that our simple single layer atmosphere model derived in class now has 2 atmospheric layers. It is transparent to visible light but a blackbody for IR a) Write the energy budgets for both atmospheric layers, for the ground, and for the Earth as a whole. b)...
  10. N

    Calculating CFM for Compressed Air Venting Down to Atmospheric Pressure

    Hello gentlemen! I'm rather new to this whole complex world we call compressed air. :) Put simply, I have spent the past 4 hours trying to find this answer anywhere and I am just not informed enough about all these numbers to get what I need to find out. I have an air cylinder that is...
  11. C

    Fermi Estimate with atmospheric pressure

    1. There are many different definitions of the location of the top of the atmosphere – the near edge of outer space. • Until around 1600, it was believed that the Earth’s atmosphere extended throughout space (recall that the Earth was also considered to be the center of the Universe until...
  12. S

    Computing Atmospheric Trajectory of Meteor

    I'm trying to understand the mathematical methods of computing the atmospheric trajectory of a meteor for two or more stations. Ceplecha wrote a rather complete description of this in around 1987. See <http://adsabs.harvard.edu/abs/1987BAICz..38..222C>. Something of a simpler version meant for...
  13. J

    What CO2 Emissions Level Would Stabilize Atmospheric CO2 Level?

    I was reading a new paper titled "Impacts of Climate Change on Marine Organisms and Ecosystems" when I came across this statement: It has been suggested that a CO2[atm] of 450 ppm is a critical threshold beyond which catastrophic and irreversible change might occur [7] this would bring a...
  14. J

    Atmospheric Opacity and laser Attenuation query

    I would appreciate assistance with a thought experiment I've been having trouble with. What I asked myself was, If I had two Lasers of equal Intensity/power, say 200 milliwatts, one appearing green and the other red, with wavelenghts of say 555 nanometres and the other 660 nm, which laser...
  15. S

    Help with piston and atmospheric pressure

    Homework Statement A cylinder with a frictionless piston of mass M and cross section S is placed vertically in an atmosphere of pressure p. The cylinder is rotated 180 degree so that the opening of the cylinder faces down. During the operation the temperature of the gas inside the cylinder is...
  16. J

    Water Pressure Calculation with atmospheric pressure corrections

    I am looking for a formula to let me obtain a pressure reading comparison for two different tests based upon the following information: I have a given flow rate in liters / minute. (same for each test) I know the size of the orifice that the water is flowing through. (same for each test)...
  17. cepheid

    Earth Atmospheric Absorption Lines

    Does anyone know a good reference for absorption lines in the Earth's atmosphere at visible and NIR wavelengths (if there are any)? For example, perhaps in the range of 3500 Å to 8000 Å? I find that the search terms are too broad to give me reasonable results on ADS. I found some atmospheric...
  18. O

    Atmospheric Density from: Alt, Temp, Pressure & Humidity

    This ones not homework, this ones just a noob begging for any help he can get, but i figured this would probably be the best place to ask. What I am doing is building a free/open source rifle 'game' for Blender3d's game engine (python scripting) with moderately accurate ballistics (several...
  19. Shackleford

    Atmospheric pressure underground?

    As you go deeper underground, to calculate the total pressure at the subterranean point, would you sum the atmospheric weight plus the weight of the overlying soil? How does this work exactly? Thanks.
  20. Andre

    Falsifying the Atmospheric CO2 Greenhouse Effect: G. Gerlich & R.D. Tscheuschner

    G. Gerlich, R. D. Tscheuschner (2009) Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics. International Journal of Modern Physics B, Vol. 23, No. 3 (30 January 2009), 275-364 (World Scientific Publishing Co.) see...
  21. wolram

    Using Telluric Lines to Measure Atmospheric Gases and Climate Change

    http://webusers.ct.astro.it/gca/papers/telluric.pdf Would it be possible to use telluric lines to give accurate measurements of atmospheric gases along with synchronous Earth temperature measurements, thus giving an index for gas abundance and variation of heat transfer through same gases...
  22. L

    Atmospheric Gas Concentrations: Exploring the Exponential Altitude Trend

    Homework Statement Derive (from the equation of motion of a neutral gas and an assumption of constant gravitational field) an expression showing why the concentrations of neutral molecules decrease approximately exponentially with increasing altitude, and why the concentration of atomic oxygen...
  23. P

    Atmospheric Pressure: Exploring Micro and Macro Perspectives

    Hey all, I have a question concerning atmospheric pressure. I understand that there are two ways to look at pressure, at micro scale (kinetic theory) and at macro scale (seeing pressure a a state variable). Now i'd like to understand atmospheric pressure using both perspectives. At...
  24. K

    Pressure, Density, and Atmospheric Pressure

    Homework Statement What is the absolute (total) pressure at the depth of 15 m below the surface of the sea. Assume density of seawater is 1.03 g/cm3 and g=10 m/s2. Give answer in kPa. Use atmospheric pressure is 101 kPa. Homework Equations P = F/A P1V1=P2V2 The Attempt at a...
  25. E

    Vapour Pressure| Boiling| Atmospheric P

    Ok I do not get WHY an object boils when atmospheric pressure is equal to Vapour pressure. Can anyone explain this? In my textbook it doesent explain it at all.
  26. Andre

    Stomata atmospheric CO2 reconstructions and hockeysticks

    The number of stomata on leafs (breathing pores) of certain plant species appears to be sensitive to the CO2 level in the atmosphere. If it is higher, it appears that these plants does not bother to make many stomata, whereas CO2 is scarce, it simply makes more stomata to extract the CO2 from...
  27. G

    KMT description of atmospheric shockwaves, anyone?

    Can anyone give me a layman's description of what happens to air molecules interacting with a supersonic object based on Kinetic Molecular Theory? Perhaps another question, how does sound waves look like at the molecular level? How does sound propagate through the random bouncing of air...
  28. G

    Creating an Efficient Atmospheric Powerplant with Hot Air Balloon Principles

    Please, write what is wrong with this reasoning: ATMOSPHERIC POWERPLANT The main idea of global warming is that greenhouse gases prevent the energy from leaving the surface of planet. In the same time the upper layers of the troposphere are much colder and successfully emit the infrared...
  29. W

    Mean surface level atmospheric density

    Homework Statement What exactly is it? How would I find it for Mars? Homework Equations The Attempt at a Solution
  30. J

    Conceptual question: Atmospheric pressure

    Homework Statement A stream of water flows vertically downward at a speed of v1 = 2.0 m/s from a faucet of cross sectional area A = 0.5 cm^2 to the bottom of a sink a distance h = 20 cm below. Homework Equations Bernoulli's P(atm) + (rho)gh = P(atm) + 0.5(rho)v^2 The Attempt at a...
  31. J

    Question Atmospheric pressure

    In Physics classes at college I was taught that atmospheric pressure is due to the weight of the air above a body. I understand this and all related equations and concepts. But just the other day I was reading up on gas laws in a chemistry book. In that book it stated that atmospheric...
  32. C

    Atmospheric Gamma Ray Interactions

    Hi, Atmospheric gamma-ray extensive air showers are induced by pair-production interactions. The equation that governs pair production is: \gamma + \gamma = e^- + e^+ My understanding of the interaction is that a gamma passes "close" to the electric field of a nucleus. The nucleus acts...
  33. Z

    Atmospheric Density - Equation to Model from Sea Level to 200km

    Hey, does anyone have an equation that roughly models atmospheric density from sea level to about 200 km up?
  34. P

    Maximizing Atmospheric Water Generation: Efficient and Sustainable Solutions

    Hello everyone. I have searched the forum and didn't find a discussion about atomospheric water generation anywhere so far. If you know of a better place for this post, please let me know. There are several companies that claim to extract water from the atmosphere. Does anyone know how to...
  35. jim mcnamara

    Atmospheric oxygen levels Cambrian -> now

    I've googled quite a bit. Other than finding articles that require payment to view I have found nothing usable. I need a source - possibly a table would be best - of estimated oxygen levels since the Cambrian. Thanks. - Reason: the only text I have was out of print during the Eocene...
  36. J

    What Color Would the Sun Appear If the Earth's Atmosphere Scattered Green Light?

    Hello, just need some guidance - I hope my logic is correct! Homework Statement So I have a scenario where the Earth's atmosphere, instead of scattering blue light from the sun, actually scatters green light based on Rayleigh scattering. I know that the sky will therefore appear...
  37. J

    Atmospheric Scattering Problem

    Hello, So I have a scenario where the Earth's atmosphere, instead of scattering blue light from the sun, actually scatters green light based on Rayleigh scattering. I know that the sky will therefore appear green, but how will the sun appear? I reasoned the sun will be magenta using...
  38. J

    What is the atmospheric pressure at the planet's surface?

    Homework Statement The density of mercury is 13595 kg/m^3. An barometer on the planet X shows a pressure reading of 1500 mm-Hg. The gravitational field strength at the surface of the planet is 12.0 m/s^2. What is the atmospheric pressure at the planet's surface? Homework Equations P =...
  39. S

    Floating Ships: Engineering a Vacuum-Filled Chamber in the Atmosphere

    How big would a vacuum-filled chamber need to be (built with currently existing materials) in order for it to displace enough of the atmosphere so it starts floating? Think about it, such contraptions would work like ships, except they don't float on water this time, but up high in the...
  40. B

    Time to Drain An Atmospheric Tank

    I am a little rusty on my differential equations as I haven't seen them in a few years! I am looking for some direction on a question on a first order ODE. I am trying to find the time required to drain a tank that is open to atmosphere. Any help would be appreciated. Thanks!
  41. G

    Calculating Force from Atmospheric Pressure on Sheila's Palm

    ok my problem is that the question asks The palm of Sheila's hand has an area of 0.0017m2.If the atmospheric pressure on the palm is 100,000 Pa, what force is being exerted on Sheila's palm by the atmosphere? I know the formula is not P=F/A I know you have to change the formula around but...
  42. T

    Atmospheric Density, exponential decay derivation

    I've read my lecture notes about 100x but can't even begin to see where this derivation can come from. A previous derivation was the equation dP/dz = -gρ (P = pressure, z = distance, g= acc due to grav, ρ = density) If atmosphere can be treated as an isothermal ideal gas of constant mean...
  43. Z

    How many exoplanets with an atmospheric oxygen signature would be necessary?

    Currently 241 exoplanets. [URL="[PLAIN]http://en.wikipedia.org/wiki/Gliese_581_c"][http://en.wikipedia.org/wiki/Gliese_581_c/URL][/PLAIN] A few are terrestrial such as Gliese c, d at 5x and 8x Earth mass; sufficient mass to be geologically active, and hence a magnetosphere, diverting a stellar...
  44. Loren Booda

    Heats generated during atmospheric entry

    Consider a hypothetical planet of given radius and mass. What atmospheric density would generate the most frictional heating on a standard sphere falling from infinity to the planet surface?
  45. S

    Atmospheric Circulation and Seasonal Variation

    How does the summer solstice affect the position of Hadley cells? I know that the solar equator is 23.5 degrees North, which differs from the 0 degrees (as a solar equator) for the equinox. For the equinox in the N. hemisphere, there are three Hadley cells, or cells of circulation. The range of...
  46. I

    Correcting for room temperature and atmospheric pressure

    [b]1. I would like to convert 1 milligram of water to mililitres at room temperature and atmospheric pressure I know that they are equivalent at3.93 celcius and an air pressure of 1013.25kPa Homework Equations 1mg=1ml at 3.93 celcius and 1013 kPa The Attempt at a Solution unsure
  47. D

    Atmospheric physics - change of temperature of parcel

    "A parcel of air is lifted slowly from the ground, where the temperature is 295K, to an elevation of 5km, and then returned rapidly to the ground. Estimate the air parcel temperature at 5km and after it returns to the groundm explanation any assumptions." I assumed an adiabatic process both...
  48. P

    Proportion of atmospheric Carbon 14

    The half-life of Carbon 14 is 5730 years and the activity of atmospheric carbon due to Carbon 14 is 255Bq/Kg. What proportion of atmospheric carbon atoms are Carbon 14. Attempted solution Decay constant for C14 = ln(2)/t(1/2) = ln(2)/5730 = 1.21x10^-4 Current activity A =...
  49. K

    How is the magnitude of atmospheric pressure determined?

    :biggrin:please tell me how it was calculated, atmospheric pressure = 760mmHg, practically and theoritically :devil:
  50. N

    Atmospheric Refraction vs Height

    I just wanted to ask a quick question that maybe someone knows off the top fo their head. How does the refraction angle of the Sun at the sunset vary as a function of the observer's height. i.e. if you are standing on a tower looking over the ocean, is the refraction deviation of the Sun at...
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