Atmosphere Definition and 407 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. capslfern

    Gasses that can be present on a planet habitable by humans

    TL;DR Summary: what kinds of gasses can be in the atmosphere of a planet without killing them or not being naturally possible I have been creating a fictional star system and ran into an issue, most of the planets atmospheres are not all the interesting, feels wrong to have most be oxygen...
  2. Astronuc

    B Asteroid 2024 RW1 - entered Earth's atmosphere over Luzon, Philippines

    https://www.esa.int/Space_Safety/Planetary_Defence/Asteroid_2024_RW1_impact_ESA_analysis How it is reported in the media - https://www.atlasobscura.com/articles/luzon-asteroid-2024-rw1 https://www.space.com/asteroid-earth-impact-september-2024-rw1...
  3. G

    B How the temperature of the Earth's surface affects the air pressure above it

    If the surface is heated, air above it will also heat, its temperature will rise. It will cause two processes: while temperature of gas rise, its pressure will also increase, but, also, as the air molecules get more energy, they will go higher from the earh surface, concentartion of the...
  4. S

    I Comparing the formation of the atmospheres on Earth vs Venus

    Read Venus stats for first time yesterday. Could the spin rate at accretion time reduce Earth's atmosphere relative to Venus, or are there moon tidal effects, e.g. mixing and carrying heat to upper atmosphere allowing escape velocity losses, to explain the 100 fold difference? I have heard...
  5. P

    I Effective Emission Height Calculation?

    This is a climate change calculation question. AGW (Anthropocentric Global Warming) theory states that as a gas gets more dense, the height at which it will release IR (Infrared Radiation) to outer space gets higher. Higher in the Atmosphere is cooler. Cooler means a lower IR output. Reduced...
  6. bruhtation

    B Gas cylinder at constant pressure being exposed to atmosphere, how?

    im learning thermodynamics and currently in a lesson about thermal processes. one process has constant pressure and before diving into equations or any proof the book provides a figure of a gas cylinder. the cylinder has a movable piston/lid on one side. the book then says "...and the piston end...
  7. D

    Opening a door between a vacuum and atmosphere

    I work as part of the engineering team running an incinerator. When the ash is removed from our furnace, it creates an open system between the furnace (which is close to being a vacuum) and the atmosphere. For many reasons, this is not ideal. We are looking to add a second door to this ash...
  8. Lotto

    What is an atmosphere comparable to Earth's atmosphere?

    Does it mean that the atmosphere is made of the same atoms and molecules like our atmosphere and that it has the same spheres such as trophosphere? And that the temperatures in these spheres are also the same or very similar like here? And are distances between these spheres the same like here...
  9. brotherbobby

    Pressure higher up in the atmosphere

    Attempt : 1. Pressure at height ##z## : ##P(z) = P_{\text{atm}}-\rho_0 gz ##, ignoring density variation. But actually, we have ##\rho(z)<\rho_0\;\forall z>0##. Hence, we are subtracting a bigger value from ##P_{\text{atm}}## than we actually should, meaning that we would end up what a smaller...
  10. A

    I Question about polarization of light by scattering in the atmosphere

    My book says: I don't understand why the bottom eye only sees the horizontal red arrow and not the other angles (black arrows)
  11. T

    B Why can't nuclear reactions burn the atmosphere

    When the US first developed nuclear weapons against the Nazis and Japan, their primary concern was whether the nuclear reactions can trigger the atmospheric nitrogen to fuse and burn the whole atmosphere. However this claim was instantly debunked by physicists. Their reasoning is that in order...
  12. Isopod

    B Could anything heat back up the core of Mars?

    My understanding of why Mars lost its atmosphere was because it cooled down too much internally and that when this happened, the planet lost its magnetic field that helped protect it from solar winds (which then ended up stripping away the planets atmosphere). Is there anything that people could...
  13. .Scott

    Adding CF4 to the Martian Atmosphere (terraforming)

    There are several possible goals related to terraforming Mars. In the short term, Earthling visitors will need to stay indoors or venture out only in pressure suits. But there would be enormous convenience and safety benefits in raising the Martian atmospheric surface pressure from it current...
  14. sideshow

    B Traveling outside of the Earth's atmosphere

    If outer space is a vacuum there is no force in a vacuum to create friction, therefore if a vehicle i.e. spacecraft space shuttle is it a vacuum and produces any amount of thrust it should move a constant through space continuing to add thrust will only make the craft move faster until it...
  15. B

    Potential Energy of the Atmosphere

    Summary:: I have been trying to do this question for a while using the hydrostatic relationship to put rho and z in terms of p, however, I can not seem to end up with an answer. Can anyone suggest where to start. The question is as follows:
  16. dedocta

    I Would Icarus' wings fly in Earth's atmosphere and moon gravity?

    Could they generate enough lift for 1/11th the weight of a human? Was picturing a giant warehouse and curious if it would work!
  17. Astronuc

    I Jupiter atmosphere, turbulence and ocean fluid dynamics

    Ocean physics explain cyclones on Jupiter https://phys.org/news/2022-01-ocean-physics-cyclones-jupiter.html Moist convection drives an upscale energy transfer at Jovian high latitudes https://www.nature.com/articles/s41567-021-01458-y...
  18. D

    Popular estimate of the Earth's atmosphere possibly wrong?

    So I just realized that on the internet the number that frequently pops up with regards to the total mass of the Earth's atmosphere is 5,100,000,000,000,000,000 kilograms. For example, the number is mentioned two times on the Wikipedia page for the Earth's atmosphere, there are more examples...
  19. S

    Condensed parts of Earth's atmosphere

    How much of Earth atmosphere consists of condensed phases? What is the breakdown of these condensed phases between those that condense in atmosphere (water) and those that do not (rock)? The total amount of water in Earth atmosphere is quoted as a 25 mm layer on average - total of about 13 000...
  20. M

    I Escape of Hydrogen from the Earth's Atmosphere

    Hi ! I ask you two questions: 1- If hydrogen escapes from the Earth's atmosphere as it happens, because if there are anaerobic bacteria that produce hydrogen naturally among some other living beings, because among the thousands and millions of years that life has been on earth, hydrogen was...
  21. B

    Changes in pressure, temp, & entropy of ideal gas in atmosphere

    So for a collection of particles each with mass m, the pressure beneath them, ##p(z)## should be higher than the pressure above them ##p(z + \Delta z)##. This is a change in force per unit area (force per unit volume I suppose) times a volume to equate with the gravitational force $$ \frac...
  22. D

    Orbital atmosphere (Karman Line -1000km)

    The Earth Rotates at complete revolution at 24 hours, the troposphere and stratosphere are dragged along with it at the equator, but what about 100km-1000km above the equator? Is there a formula or chart that astronomers can use to predict the tiny amount of drag that satelites have to encounter...
  23. Limebat

    Atmosphere and volume - vacuum cannon limitations

    https://physics.csuchico.edu/~eayars/publications/AJP00961.pdf http://www.phys.utk.edu/demoroom/MECH/The%20Vacuum%20Canon.pdfSo I get the outside atmosphere is what provides air density and such in the pdf above^. However, why is it that most cannon demonstrations use just the air from the...
  24. T

    Oxygen Extracted from Martian Atmosphere - a first

    On April 20, 2021, an experiment on the NASA Perseverance Mars Rover broke down the CO2 Mars atmosphere to 2CO + O2. That makes it the first instrument to produce Oxygen on another world. Still a ways to go, design maximum is 10 grams per hour, people need around 60 grams per hour...
  25. Epsilon Eridani

    Turning oxygen into fluorine in our atmosphere

    Summary:: Hypothetical discussion of a method to turn oxygen into fluorine through the use of another chemical and also discussing the biological effects of fluorine. Hello, I'd like to start this by saying my knowledge of chemistry is extremely basic. I barely graduated chemistry in high...
  26. LCSphysicist

    Thermodynamics: work done on the atmosphere by an expanding gas

    V = V(n,P) PV = nc dV = (-cn/P²)dP + (c/P)dn dW = (cn/P)dP - (c)dn This was how i tried to attack the problem, but it will end with log and probably it is wrong, any tips to fix it?
  27. Mikkel

    Meridional Heat Transfer - Ocean and Atmosphere

    Hello! I'm currently studying meridional heat transfer, but I'm struggeling to understand the attached figure. I don't understand why the ocean contributes more than the atmosphere near the equator and why it suddenly falls off towards the mid-latitudes. Also, why the atmosphere peaks at...
  28. Algr

    Terraforming the Pre-Earth? (Algol's video)

    I find this video absolutely amazing, and have watched it over a dozen times now. It helps if you can use the spacebar to pause it and read the text, and arrow keys to back up 5 seconds. - This is NOT phone friendly! Big monitor and 1440p recommended. So two different questions for...
  29. sciFax

    I Effects of hydrogen anions in the solar atmosphere

    What is the population density of ##H^-## hydrogen anions in the Sun's atmosphere, how stable are they, what limits their numbers, and since they are the dominant source of opacity in radiative transfer in stellar atmospheres, what do they effectively "hide"?
  30. Khatti

    What's going on with mining carbon from the atmosphere?

    <Mentor moved thread to Science Fiction> Hello one and all. I'm fascinated by the idea of breaking down methane and carbon dioxide and using the carbon as a building material (graphene being the preferred material rendered from this process). Can anyone tell me anything on where the current...
  31. J

    A Is this evidence that Venus originally had a nitrogen atmosphere?

    Has MESSENGER found evidence that Venus originally had a nitrogen atmosphere, and might have been more habitable, and the present amount of CO2 was released by some cataclysm afterwards? https://phys.org/news/2020-04-lucky-messenger-upends-long-held-idea.html
  32. Zohar

    Viscoty and Surface tension -- depends on the composition of the atmosphere?

    why isn't Surface tension reliant on the composion of the atm? For an instance; If you place a glass of water in a room with regular atmosphere or you place it in a room filled with other gasses. The coefficient of surface tension of the fluid will change? Maybe? why isn't viscoty of a fluid...
  33. Bob Enyart

    I Do We Need ESC in Earth's Atmosphere?

    Einstein's synchrony convention (ESC) defines the one-way speed of light as equal to the roundtrip speed IN A VACUUM, at least, the discussions and papers I read on it (even Einstein's 1905 paper) always seem to set the context as in space (a near vacuum) or in a (theoretical) vacuum. I'm...
  34. B

    Density of air at one atmosphere pressure

    How would I tackle a problem like this? I made a start by writing down the ideal gas equation and then done some manipulation on both sides to get the density expression of the ideal gas. I'm not sure if this is what the question wants as I'm dealing with 2 different types of gases in the same...
  35. K

    A Exploring Rocket Exhaust Plume Molecules in the Upper Atmosphere

    I'm pondering the behavior and persistence of rocket exhaust plume molecules far above the atmosphere. For example, the plume from an apogee circularization thrust from GTO (Geosynchronous Transfer Orbit) to GEO (Geosynchronous orbit). CO₂ and H₂O are among the molecular species emitted by a...
  36. S

    Earth's Atmosphere -- Is gravity the reason we have air pressure?

    I have read an article in Quora, where a person says that "Gravity pulls the atmosphere towards itself and that's one of the reason why our Atmosphere is still this way" and also adds that, "gravity is the reason we have air pressure in the first place. Gravity pulls on the atmosphere...
  37. S

    Store wood in old salt mines to reduce CO2 in the atmosphere

    If trees are cut and then burned they have not reduced the CO2 in the atmosphere at all. And if they are left in the forest and then rot 90% of their mass also go back into the atmosphere. Here in Germany we have many old salt mines. I wonder if it would be a good idea to cut trees and store...
  38. H

    Detecting CO2 in the atmosphere

    I didn't notice this forum section until just now, I noticed it as I was scrolling down to the general area to ask if anyone knew of a forum that deals with climate science. What ways can we detect CO2 in the atmosphere. I've seen some social media posts that show an image of South America that...
  39. B

    Exploring Sound in Low Atmosphere: Speed, Intensity, and Frequency

    There is no sound in space because there are not enough particles to transmit the pressure wave. But what about really high in the atmosphere where there is just a little air? Would sound move faster, slower or at the same speed? Would the intensity (aka volume) go up, down, or stay the same...
  40. Fabrizio Vassallo

    What is the composition of the Earth's exosphere?

    Hello! My name is Fabrizio, I'm a high school student doing some research on the atmosphere. Right now, I'm trying to figure out how much matter escapes into space via Jean's Escape. I've found several formulas, all of which require me to know what the amount of particles per m3 of a certain...
  41. J

    I Probability distribution of angle of asteroid entry to the atmosphere

    Used to play with gravitational attraction simulations ages ago. One thing I noticed it was difficult to get a small object to collide with a bigger spherical one vertically and far more likely to hit at an angle far from 0. Has the math of this been worked out for asteroids entering the Earth's...
  42. K

    Pressure Difference Between the Inside and Outside of a Balloon

    Hello all. I have a question about gasses and pressure: Is there a way to calculate how strong a material making up a balloon has to be to withstand a given pressure difference between the inside and outside? In other words, if I have a balloon I need to fill to a pressure of 10atm inside vs...
  43. D

    Misc. Hydrostatics problem in a water vessel

    I am trying to design a water vessel system that maintains it's water level as it is consumed. In item 1. It's a simple water barometer, where the height of water in the column can be supported by atmospheric pressure until 10.34. In item 2. There are two columns that are open to atmosphere...
  44. P

    A Acceptable Atmosphere for CZ/Float-zone Refining

    Both the cz (Czochralski Process), and Float-zone refining of silicon require an inert atmosphere, usually argon. How pure does the argon atmosphere have to be? How high of a vacuum has to be pulled before releasing argon into the tank?
  45. Drakkith

    I What factors determine the composition of a planet's atmosphere?

    I'm curious as to how the mass of a body affects the kind of atmosphere it can hold. I know that Earth tends to lose its lightest gases over time, which is one reason why helium doesn't build up in the atmosphere, whereas planets like Saturn and Jupiter have held on to lots and lots of hydrogen...
  46. Spinnor

    Using Aircraft & Balloons to Deliver 'Sunscreen' to Upper Atmosphere?

    In the news we learn that aircraft (that don't exist) flying to 12 miles in altitude might be used to deliver "sunscreen" to the upper atmosphere. Could we use a carbon fiber fabric to make a strong, relatively lightweight, and flexible smokestack that might be supported by large helium lifting...
  47. wolram

    Is Bitcoin Mining Contributing to Climate Change?

    https://www.sciencedaily.com/releases/2018/10/181029130951.htm What do you think the advancement of technology is doing to the Earth?
  48. D

    B What would happen to Earth's temperatures without an atmosphere?

    Hi everyone I've read that if Earth had no atmosphere it'd be completely frozen over with temperatures around 255K. Why is this the case when the moon has daytime temperatures of 373K (and night time temperatures of 100K)? Why wouldn't the oceans thaw during the day? Are they just too big...
  49. K

    Atmospheric Refraction: Temperature, Distance, Object Shape

    Does atmospheric refraction only work at certain temperatures, distances, and shape of the object (i.e. only spheres)?
  50. Jed K

    How does water vapor in the atmosphere form under normal conditions?

    So I understand generally how humidity in atmospherics work but there's this one thing I can't reconcile with the fundamentals. First, my understanding of the basics. Water boils at 212 F @ 14.7 psia (1 ATM). At 213F @ 14.7 psia that water is now 1F superheated vapor. So we're all on the same...
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