What is Atmospheric: Definition and 270 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. Miguel Velasquez

    Forces due to atmospheric pressure won't cancel in an open tank

    Homework Statement [/B] I am trying to understand why books always point as a fact that hydrostatic force on the bottom of a open liquid filled tank doesn't depend on the force due atmospheric pressure because they these forces cancels each other. Homework Equations [/B] P=[P][/o]+ρgh F=P*A...
  2. S

    Conceptual Issue Dealing With Atmospheric Pressure

    Homework Statement A 1m^3 steel cube is to be floated on mercury (specific gravity=13.6). On each side of the cube there is a 5mm clearance. Assume that the container is open to atmospheric pressure at 100kPA. Find the mass of the mercury. Homework Equations P=F/A The Attempt at a Solution I...
  3. Tone L

    Schools Graduate schools with Planetary Sciences

    I was curious if anyone knew of any schools that offered graduate degrees in planetary sciences, specifically studying other planets atmospheres. May be it the study of the atmosphere itself or remote sensing techniques for planetary atmospheres. I know how to find schools that offer the...
  4. Delta Force

    Newly Declassified Atmospheric Test Footage

    Lawrence Livermore National Laboratory recently declassified some footage of atmospheric nuclear tests and posted them to Youtube. You can see the videos here.
  5. E

    I Atmospheric Photolysis and its relation to Absorption Cross Section

    Dear Forum: I have a question about atmospheric photodissociation. I use methane as an example, but any atmospheric gas molecule would suffice. Methane, CH4, has a photodissociation energy of 439 kJ/mole at 298oK, meaning that CH4 + hv --> CH3 + H , hv<274nm. It also has an “absorption cross...
  6. sistruguru

    Relative Humidity (RH) affecting atmospheric attenuation of light?

    Ok, so I have another question that online searches have not been able to produce. Everything I've seen online references sound waves, or RF signals, or electromagnetic waves. I know that the reason we can view sunsets and sunrises safely is because of atmospheric attenuation - the amount of...
  7. M

    Atmospheric Pressure: Solving with a Mercury Barometer

    Homework Statement A mercury barometer located in a room at 25°C has a height of 750 mm. What is the atmospheric pressure in kPa? Homework Equations Patm = ρ*g*H0 The Attempt at a Solution [/B] My question pertains to the units and how it ends up as kPa in the book. I have no problem with...
  8. sophiecentaur

    I What Causes Distinct Absorption Bands in the Sun's Spectrum During Sunset?

    I recently bought a cheap and cheerful hand held spectroscope. Great fun to look at CFL lamps and the modern LEDs. Those LEDs are really good, btw. Also, the 'scope gives a pretty even spread of brightness over the whole visible range. (an equipment check). I have been looking at the spectrum of...
  9. E

    Studying What are Possible Thesis Topics for Atmospheric Physics?

    Can you suggest possible master thesis topics relating to atmospheric physics? I have a bachelor's degree in physics and I mostly comfortable in numerical and theoretical physics. Since this field is somewhat new to me, I need to have a number of options on what topics to choose from. Thank you...
  10. VNV

    Writing: Input Wanted Extraorbital Atmospheric Re-Entry: Terminal Velocity?

    Extra Orbital Atmospheric Re-Entry, or the Art of Leaping From Orbiting Starships onto Planets. Ignoring that my TITANs are donned in A.T.L.A.S. PCA and thereby protected by force-evaporating malarkey nodes, I want to know how they'd be in the middle of these jumps. In my book, a TITAN Super...
  11. D

    Calculation of atmospheric presure

    Homework Statement Taking atmospheric pressure at sea level to be 1x10^5 pa CPa and the density of air at sea level to be about 1.2kg/m^3,estimate the atmospheric pressure in London 550m above sea level. For this calculation, it is easiest to assume that air density doesn’t change with height...
  12. D

    Atmospheric Pressure on Shaft of piston cylinder assembly

    Homework Statement In a vertical piston cylinder assembly, a vertical shaft whose cross sectional area is 0.8 cm^2 is attached to the top of the piston. Determine the magnitude F, of the force acting on the shaft, in N, required if the gas pressure inside the cylinder is 3 bar. The masses of...
  13. F

    Estimating Atmospheric Params w/ Autocorrelation & Spectral Density Funcs.

    Homework Statement An experiment probes a coherent process and the receiver is coherent. The autocorrelation function and the spectral density function are estimated and transformaed into atmospheric parameters. See Table 1 below 1) Calculate the maximum velocity (in m/s) that may be...
  14. nomadreid

    What does GPS do about atmospheric interference?

    Although microwaves are not refracted much in the atmosphere, there is some, and the atmosphere does vary a lot, and the GPS depends on a pretty exact timing of the signals between ground to satellite. So how do GPS systems take the atmospheric refraction into consideration?
  15. mfb

    I First atmospheric spectroscopy of Earth-sized exoplanets

    The Hubble telescope lead to the first spectroscopy of the atmospheres of two Earth-sized exoplanets, TRAPPIST-1b and TRAPPIST-1c. A large hydrogen/helium atmosphere could be ruled out - not that surprising, but still nice to have this confirmed. The main star, TRAPPIST-1, is just 40 light...
  16. Ravi Singh choudhary

    Why atmospheric pressure does not crush us?

    1atm is typically something 101.13 kPa that means 100kN force is acting on 1 square meter surface area of our body. How we are capable for taking such high pressure? Sometime I think on 1 square cm area what immense force they are creating. I feel something is wrong with my concept of...
  17. Ravi Singh choudhary

    What pressure not increases if I seal the container?

    CASE1: A container with some water is open to atmosphere, pressure is definitely atmospheric, no somehow I put cover over it and sealed it also. Pressure would increase because new equilibrium will establish between water and its vapour so pressure will increase in the closed container. CASE2...
  18. T

    How to calculate atmospheric pressure?

    Let's say I had the composition of an atmosphere, the mass of the planet it was on, and the diameter/density of said planet. First, what else, if anything, would I need to find the atmospheric pressure? Second, what would the equation for doing so be?
  19. H

    How much atmospheric pressure is exerted on the human body?

    I understand that this will vary from human to human, but how much weight is exerted, in total, on the average adult human body. It would be very much appreciated if the calculations can be shown. Thanks!
  20. T

    Atmospheric Physics: Brunt Vaisala frequency question

    Homework Statement Gravity Waves. Consider a pattern of motion in which fluid elements move at an angle θ to the vertical. Show that for an atmosphere where the Brunt-Vaisala frequency is ωB the elements will oscillate with a frequency ν = N cos θ. Homework Equations , -Brunt Vaisala...
  21. dmetrd

    Confused about why atmospheric pressure won't move piston

    I'm feeling pretty silly not being able to understand this. Let's say that you have a piston (red) sitting inside of a housing (black) like this Let's say that something like this was lying on its side on a flat table. By my understanding, if the contact between the piston and the housing...
  22. y2j

    Measuring Pressure in Lab: Add Atmospheric?

    When we take pressure readings by pressure gauge (Bourbon pressure gauge or pressure transducer) in the laboratory for any fluid system ,in this case, is the atmospheric pressure value (1 bar) must be added to this readings when we use them in any calculations later or them must be used...
  23. Andy Resnick

    Atmospheric Optics: Moon 22° Halo & Paraselenic Circle

    Took this image of the moon a couple of days ago. It shows the 22° halo and if you squint and imagine, part of the paraselenic circle. for more info: http://www.atoptics.co.uk/halo/common.htm
  24. cyriac

    Atmospheric pressure and weight measurement

    Whats the significance of Atmospheric pressure being refereed as 100kPa ? Does that really mean 10000 kg/m2 acting upon us ? If we are measuring only collision force on the surface and not the weight of the entire column of air above us, then why figure 100kPa (100000 N force/m2) which is huge...
  25. J

    Electrical DIY Atmospheric Carbon Dioxide Detector?

    I thought it would be an interesting project to build a detector that will measure and log the outdoor atmospheric CO2 levels. These (global average) levels are currently about 400ppm and these (global average) levels vary by a few ppm every year. Looking for a sensor though, I can't seem to...
  26. H

    Atmospheric Pressure: Why is it Equal?

    Hello everyone! As we've known, the pressure at the bottom of a volume of gas is define by its weight times the height. So I wonder why the atmospheric pressure is equal in all direction? Many thanks
  27. T

    Delta-v to overcome atmospheric and gravity drag at 13km?

    Wikipedia says that: Atmospheric and gravity drag associated with [space] launch typically adds 1.3 to 1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s (28,080 km/h). Does anyone know, or know how to calculate/estimate/simulate the delta-v...
  28. K

    Some Thoughts on Atmospheric Systems

    Atmospheric sciences are—much like the sister science of astronomy—primarily observational sciences and not primarily experimental sciences. The atmospheric systems that we study are not well-defined systems under controlled conditions, but ill-defined systems under completely uncontrolled...
  29. P

    Gauge pressure and atmospheric pressure

    Homework Statement Objects A and B are submerged at depth of 1m in a liquid with specific gravity of 0.877. Given that density of object B is one third that of object A and that the gauge pressure of object A is 3atm, what is the gauge pressure of object B? (assume atmos pres is 1 atm and that...
  30. R

    Why does atmospheric pressure not affect SVP?

    I'm an anaesthetist... I have exams coming up... I use lots of gases and vapours and need to appreciate the associated physics. My question relates to saturated vapour pressure and ambient pressure... SVP increases with temperature - more molecules have sufficient energy to escape the...
  31. LittleMrsMonkey

    Programming languages in atmospheric physics

    I do know this is very vague and maybe a little bit dumb. But are there languages that are ,generally,used much more than others in atmospheric physics?Excluding meteorology. I put this thread in Academic Guidance because this question is translated to "What computer languages should I focus on...
  32. Hyo X

    Atmospheric oxidation generating voltage?

    Imagine a sample on an insulating chip. The material sample is contacting two electrodes. The material (a composite, could have liquid component) has a uniform, presumably amorphous, structure between the electrodes - i.e. it is not patterned with different layers. Is there such a material...
  33. ChrisVer

    Why ratio atmospheric ##\nu_\mu : \nu_e = 2:1##

    Why is the ratio of atmospheric neutrino fluxes expected to be: R= \frac{\nu_\mu + \bar{\nu}_\mu}{\nu_e +\bar{\nu}_e} =2 for no Neutrino Oscillations? An answer that I found gives: \pi \rightarrow \mu \nu_{\mu} \rightarrow e \nu_e \nu_\mu \nu_\mu But I think this is "wrong" in general, because...
  34. Thom_Silva

    Hydrostatic and atmospheric pressure

    So I've been wondering, 10.3 meter of water amount for one atmosphere, and according to Pascal's law pressure can compute by P=P0+ ρgh. If we have a glass with 10 cm of water inside , the pressure in the glass would be lower than atmospheric pressure and therefore when you turn the cup upside...
  35. Jimster41

    Atmospheric CO2 removal technologies?

    Are there any legitimate candidates for technologies that might provide inverse leverage over atmospheric CO2 levels? Super trees, Algae towers, I don't know, anything at all? I'm just asking about atmospheric control technologies, not about climate change per-se. of course the wiki has some...
  36. U

    How much will the atmospheric carbon dioxide change?

    Homework Statement Suppose ##10^{14} kg## of carbon dioxide was released into the atmosphere and absorbed completely, what is the percentage change of carbon dioxide concentration? Take initial atmospheric mass mixing ratio to be ## 5.7 \times 10^{-4} kg/kg##. Homework EquationsThe Attempt at...
  37. Anchovy

    Understanding Gaisser's atmospheric muon parameterization?

    Hi all, I'm wondering about an equation for the differential flux of atmospheric muons that looks like this: \frac{dN_{\mu}}{dE_{\mu}} \approx \frac{0.14 E^{-2.7}}{cm^{2}.s.sr.GeV} \Bigg\{ \frac{1}{1 + \frac{1.1 E_{\mu}cos(\theta)}{115 GeV}} + \frac{0.054}{1 + \frac{1.1...
  38. E

    How does Atmospheric Correction work?

    I have been reading about it a lot, but I still cannot grasp the concept and procedure of Atmospheric Correction. If, for example, a have a raw image from a satellite, how does Atmospheric Correction do its processes, and what would be the expected resulting image?
  39. A

    Atmospheric Substitution Reaction

    There is an ever constant increase of CO2 and CH4 in the atmospheric, thanks to global warming and greenhouse gases. I came across this equation while looking over changing gas compositions in the atmosphere. CO2 + CH4 ----> 2H2O + C2 Can someone explain me how I can figure out the amount of...
  40. H

    Earth's rotation related to atmospheric motion

    How much affect does the rotation of the Earth (such as drag friction) have on the motion of the atmosphere (if any). Respectfully, Hagar
  41. R

    Atmospheric humidity for water production.

    *Suggestions for Water Production for California.* California is still in the midst of a huge drought: Annie Sneed Science 03.23.15 7:00 am California’s About to Run Out of Water. We Have to Act Now. http://www.wired.com/2015/03/californias-run-water-act-now/ There appear to be however...
  42. A

    How to Calculate Energy for Atmospheric Molecule Reaction and Isolate Gases?

    The atmosphere consists of two toxic, and unfortunately abundant gases in our atmosphere. Carbon dioxide and methane. Carbon dioxide produced by factories are not needed in the atmosphere and cause harm. So is methane. Acegikmoqsuwy and I thought of an equation to solve this problem: CH4 + CO2...
  43. N

    Do atmospheric muons accelerate?

    <<Moderator note: This discussion was originally posted in another thread. It has been moved as it did not concern the OP of that thread.>> The muons never accelerate from A->B?
  44. bohm2

    DNA stable during atmospheric transit and re-entry

    DNA survives critical entry into Earth's atmosphere http://www.sciencedaily.com/releases/2014/11/141126144150.htm Full published article: http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0112979&representation=PDF
  45. Gotaskor

    Atmospheric Extinction: Calculating Visible & Radio Wave Opacity

    I'm wondering if anyone can help me with something. I've been asked to calculate, assuming no curvature for the Earth, how far through the atmosphere one could see when stood at sea-level - as in, at what distance would the atmosphere become opaque, both to visible light and to radio waves. I...
  46. B

    How Is Delta V Loss Calculated for Spacecraft?

    How do you calculate how much delta v is lost from gravity and atmospheric drag? I've been looking for days but I can't find anything that actually tells me how it's calculated. For example it takes 1.5 km/s - 2 km/s extra delta v for a low Earth orbit because of drag loss, how was that number...
  47. H

    Ammonia Gas: Vapor Pressure > Atmospheric Pressure

    This is for "ammonia". The problem says that ammonia is a gas at room temperature. And that this tells us: "the fact that ammonia is a gas at room temperature tell us that vapor pressure of ammonia must be greater than atmospheric pressure". I know that for water, when the boiling point is...
  48. B

    Thermodynamics atmospheric pressure Question

    Homework Statement A liter of air, initially at room temperature and atmospheric pressure, is heated at constant pressure until it doubles in volume. Calculate the increase in its entropy during this process. so Ti= 300K, Volume which is 2Vi=Vf; Pressure is constant Homework Equations ΔS...
  49. H

    Vapor Pressure vs Atmospheric Pressure

    Homework Statement If the boiling point is the point at which vapor pressure > atmospheric pressure, so all of the water molecules can break free and fly into the atmosphere (i.e. overcoming the atmospheric pressure), then why is it that when atmospheric pressure > vapor pressure, the...
  50. Y

    How does atmospheric pressure work?

    From what I know, the pressure of a gas is due to the collisions of its molecules against a surface. So I don't understand why atmospheric pressure is measured by taking the weight of all the air molecules above a surface including the ones that aren't contacting it. Gases have plenty of space...
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