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. Vanadium 50

    What Could Cause a Persistent 250 Hz Hum at Night?

    Last night I head a very odd hum. I believe it was atmospheric, but did not see the source. It was at 10PM It came from the north. It did not noticeably move. It was about 250 Hz. It was not a perfect sine wave - there was some distortion. More or less like an engine. It lasted about 4 minutes...
  2. Astronuc

    How Does the Jacchia Model Predict Atmospheric Drag for Satellites in LEO?

    The subject was part of a presentation today on orbital determination and orbital mechanics. Lots of variables to consider, but in particular for satellites in LEO, how much drag occurs in the atmosphere, and how does it vary peridically (day/night during an orbital period), seasonally (as the...
  3. Aurora Program

    Is it possible to transform an electric thunderstorm into an EMP storm?

    TL;DR Summary: Do not get confused with the title, standard thunderstorms are not generally classified as EMP storms because they don't have the power, the scale and nature of the electromagnetic energy involved are greatly different compared to a nuclear EMP detonation, that's exactly the...
  4. L

    Atmospheric pressure and water pressure - Boyle's law

    I am a bit confused on the marking scheme as attached above. P1V1 is a constant by Boyle's Law. If the volume increases by a factor of 3, then the pressure decreases by a factor of 3. This means that the pressure at the top is 1/3 the pressure at the bottom, right? The pressure at the top is...
  5. G

    Calculating atmospheric partial pressure of oxygen

    I study genotype-environment associations in alpine species. I frequently see altitude as the sole predictor of partial pressure of oxygen in the literature concerning hypoxia adaptations. However, I understand that partial pressure of oxygen is also influenced by temperature, humidity, and...
  6. T

    B Atmospheric pressure, vacuum, etc.

    The value of the atmospheric pressure does not seem to me to be correct 1013 HPa and can be recalculated as approx. 1kg/cm2 (is it true?), but it does not seem that such a pressure would be manifested by any resistance or any deformations, for example on a folded sheet of paper. It is possible...
  7. C

    What does atmospheric pressure have to do with the gauge pressure?

    In this video( ) it's explained what is gauge pressure. Can someone please explain to me what does atmospheric pressure acting on a tube(in video at 3:51) has to do with displacement of a tube? I understand that the atmospheric pressure acts on the tube, but in the open space that does not...
  8. L_ucifer

    How does relativity affect the detection of atmospheric muons?

    TL;DR Summary: I got this question on a quiz for a Coursera course on special relativity, and I'm confused about the answer. I've detailed my thinking below any help on where I went wrong would be greatly appreciated. Question. Muons are unstable fundamental particles. In its own rest frame...
  9. M

    Solving Fluid Statics Problem: Accounting for Atmospheric Pressure

    Hi! For this fluid statics problem, One of the answers is: However, why did they assume the pressure at the top was zero? I thought the pressure at the top would be 1 atm? So tried to take atmospheric pressure into account putting 1 atm at the top, Do you please know how to get P_0A/2 so...
  10. Zuzana

    A Atmospheric electron neutrinos

    Hi, I would like to ask question about atmospheric electron neutrinos. It is known that atmospheric electron neutrinos originate from the decay of muon in the atmosphere, but we can also calculate that muon with energy more than 10 GeV is able to penetrate about 100 km, so it does not decay and...
  11. K

    Producing Renewable Liquid Fuels from Atmospheric Carbon Dioxide

    The Sasol plants in South Africa are producing liquid fuels using coal and water as the source of energy and syngas, CO and H2. Some refineries are using natural gas as the starting fuel to produce liquid fuels. Both of these processes are not renewable. The US Navy has a process to extract CO2...
  12. Jonathon

    How to factor atmospheric pressure into relative humidity calculations

  13. Galexy

    Atmospheric pressure inside a protoplanetary disc

    Summary:: Could there be a place in a newly forming protoplanetary disc where the gas pressure and temperature would be anywhere close to survivable? I am writing a fiction story that takes place there, and I want to know how far from reality this premise would be. When a protoplanetary disc...
  14. D

    I How is the popular estimate of the Earth's atmospheric mass correct?

    There is a number floating around on the internet that says that the mass of the Earth's atmosphere is about 5 quintillion kilograms. The way that that number was calculated was through knowing that per square meter of surface area at sea level, about 100,000 Newtons of force is applied, which...
  15. D

    Is Anthropogenic Climate Change Still Debated on Science Forums?

    I'm wondering if anthropogenic climate change (C13: C14 and C14:C12 ratios) is still contentious on these forums. Counting the amount of fossil emissions in the last 100 years isn't particularly difficult, and matching the curve with NOAA measurements seems trivial, so I'm wondering what kind of...
  16. Krokodrile

    Hi determine the height of the mountain (using atmospheric pressure)

    i have the first convertions of the atmospheric pressure: 1872 lbf/ft^2 = 89,632.6 Pa 2016 lbm/ft^2 = 96,325.4 Pa g= 9.72 m/s^2 But, i don't have idea how pass the air density of "lbm" to international units ;,(. And other cuestion: its fine pass lbm/ft^2 and lbf/ft^2 to Pa simirlarly?
  17. K

    Atmospheric pressure as a function of altitude

    Summary:: i) Set up a differential equation that describes how the pressure ##p## varies with the distance r from the center of the planet. Hint: You can base your reasoning on static equilibrium and Archimedes' principle. ii)Calculate how the atmospheric pressure p and the density of the...
  18. Miles Behind

    Simple atmospheric question re: Mars

    Assuming that both the Earth and Mars's atmospheric pressure follows an exponential curve, how many kilometers deep would the average bore-hole on Mars need to be in order to arrive at a depth where the atmospheric pressure was 0.35 bar or approximately 5 psi? What about 0.7 bar?
  19. Russ Edmonds

    Fishing for atmospheric electricity

    Fishing for atmospheric electricity.Three microcuries of Am-241 were placed in a aluminum pie tin. The pie tin was then suspended 2.7 meters in the air by a fishing pole. The pie tin was insulated from ground by the nylon fishing line. A wire connection was hung from the pie tin to the top...
  20. anonymous99

    Why doesn't atmospheric pressure crush us?

    H
  21. Deepesh

    Regarding Standard atmospheric conditions

    Why do we take ISA conditions(Atm. Temperature, Atm. Pressure) as static and not stagnation? Thanks
  22. T

    Impact of Atmospheric Pressure on the Water in a Tank and a Pipe

    Hello all I was hoping someone could help with understanding how fluids level out under atmospheric pressure. For example:- Below is a picture of a tank of water with a closed door at the bottom, the door leads to an inclined pipe that is closed off at the end there is another pipe connected...
  23. Graeme M

    Contribution of surface heat to atmospheric warming

    I'm not sure if this should be here or under Earth Sciences. GHGs warm the atmosphere, but they do that largely in response to LWR from the heated surface. The relative contributions of the major GHGs are known, but I can't seem to find anything about the contribution from surface heat. For...
  24. D

    Atmospheric absorbance of CO2 and impact of increaseing concentration

    This is a serious question, and it is not meant as an attempt to "debunk" greenhouse warming of the earth. Wikipedia has the below image, which shows the atmospheric transmittance as a function of wavelength. Notice the red vertical line through one of the CO2 absorption bands. We see that the...
  25. Rensslin

    B Atmospheric Burn-up During Re-Entry

    I can’t get my mind around how things “burn-up” upon entering the atmosphere. I envision some kind of bellyflop. Objects have no friction prior to entry. But how is this different from an acceleration within the atmosphere? Is the speed of the object faster than can be attained within the...
  26. N

    I Impact of atmospheric turbulence on secret key rate in QKD

    I have the calculation on secret key rate over the turbulence channel using Python code. The calculation is as below: import numpy as np import math import re import random import cmath #import itertools from math import pi,e,log import time #import xlwt import matplotlib.pyplot as plt from...
  27. C

    Atmospheric CO2 absorption - actual quantification?

    I have read oodles of hand wavy qualitative text about 'the greenhouse effect' and it is clearly dominated by the absorption characteristics of H2O vapour. What I struggle to understand is the part of CO2 in radiative absorption, in relative quantified terms. CO2 has absorption peaks at 2.7um...
  28. C

    Why is air in atmospheric pressure and room temperature a gas?

    This seems like a simple thermodynamics question but I would like clarification. So the absolute critical temperature is 132.5 K (-221.17 F) and the absolute critical pressure is 3.77Mpa (546.7 psi). I understand that for temperatures above the critical point, a pure substance undergoes an...
  29. dlgoff

    Atmospheric pressure -- Record low in Kansas?

    Here's a print screen from my weather station's computer early this morning. I've never seen this low of atmospheric pressure here in Kansas before. Shortly after midnight the pressure hit a low of 28.08 InHg. :oldsurprised:
  30. T

    Atmospheric pressure per square cm

    Hi, I have a problem to understand one small thing. They say that air pressure per square cm at sea level is approximately 1 kg. So at 2 sq cm it will be 2 kg, at 3 sq cm it will be 3 kg etc. But... Here where I have a problem. The thing is that inside 2 square cm you can put 4 one square cm...
  31. A

    Flight Path Angle and Velocity During Atmospheric Re-entry

    A space vehicle enters the sensible atmosphere of the Earth (300,000 ft) with a velocity of 25,000 ft/sec at a flight-path angle of -60 degrees. What is its velocity and flight-path angle at an altitude of 100 nautical miles during descent? (Assuming no drag or perturbations, two body orbital...
  32. M

    I Atmospheric Flow: Meaning & Natural Examples

    What I need is just what does it mean Atmospheric flow? how or where can someone find it in the nature?
  33. B

    I Atmospheric Lapse Rate (calculating the altitude of cloud formation)

    This is probably more of a p-chem question but I figure you guys are smart enough to answer this. FREEZING LEVEL CALCULATION: Per FAA "A standard temperature lapse rate is when the temperature decreases at the rate of approximately 3.5 °F or 2 °C per thousand feet up to 36,000 feet" Easy...
  34. J

    CO2 and the correlation with rising atmospheric temperatures

    I just read the policy for this forum "Earth" so i hope my next question will be approved, it is with the best intentions. My friends and i where having a discussion about CO2 and the correlation with the raising temperature, we know that CO2 is a greenhouse gas. About that, CO2 is a greenhouse...
  35. S

    Is atmospheric pressure gravitational or kinetic?

    I keep seeing a popular question asking about atmospheric pressure "crushing" us. The word "crush" throws me off. It is my understanding that air molecules create pressure due to collisions. In other words, the molecules exert pressure due to having kinetic energy - and the more molecules you...
  36. opus

    Atmospheric pressure- where do we get the mass?

    At sea level, we experience an external force pressing down on us at any given time which is equal to about 15 pounds per square inch. Pressure is defined as: ##P = \frac{Force}{Area}## where Force is equal to mass x acceleration. When we say that we experience this 15 pounds per square inch of...
  37. D

    Ocean acidification and atmospheric carbon

    Hi everyone The following graph shows levels of CO2 in the oceans increasing with atmospheric CO2. https://ocean.si.edu/conservation/acidification/ocean-acidification-graph Given that global temperatures should rise with CO2, is it theoretically possible for the oceans warm to the point...
  38. Ryan_m_b

    I Atmospheric hazing on an infinite plane

    A question came up with some friends recently that googling hasn't turned up a satisfying answer to. Simply put: If the world was flat and infinite (ignoring all the stupidity of this) how far could you see from sea level before the atmosphere itself is preventing any light reaching you...
  39. 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)?
  40. B

    Why is carbon dating not affected by atmospheric CO2 levels?

    When I read about carbon sinks and the production of CO2, I am puzzled by the trust we have in carbon dating. If I understand correctly, C14 is produced by cosmic rays and nitrogen and is considered a very steady process thus carbon dating is trusted. But if C14 is brought into biological...
  41. J

    I Atmospheric CO2 and diurnal Asymmetry

    Something that has bothered me is that CO2 appears to have a much greater role after dark than in the daytime. I was wondering if this is because of a CO2 population inversion during the sunlight hours. I am thinking that Sunlight and daytime blue sky, excite atmospheric nitrogen, The nitrogen...
  42. D

    Bizarre Atmospheric Physics Problem

    Homework Statement For an atmospheric physics class, we are given this problem that I and a classmate have been struggling with for days. Reaching out here for some help. Full Problem statement in the image attached. We have a balloon at 293 K and 101,300 Pa. How much fuel is needed to raise...
  43. D

    About atmospheric remote sensors

    Hi I am currently involved in atmospheric remote sensors on board a satellite which collect back-scattered and reflected solar radiation to provide atmospheric composition measurements through an algorithm based on Differential Spectroscoy. I am currently involved in studying the physical...
  44. C

    B What warms atmospheric nitrogen?

    Is there a particular narrow band of EM frequencies that nitrogen absorbs to increase its temperature?
  45. Laurie K

    B Basic rule for Atmospheric Reentry of Glider Class vehicles

    The Chinese Space Station, Tiangong 1, looks very much like a glider i.e. a bit like the US Space Shuttle (solar panels are made of similar materials to Space Shuttle tiles with much less friction), as the German radar images show in the link below, so it most likely wasn't tumbling but yawing...
  46. I

    Can the Ground Temperature be Expressed in Terms of the Emission Temperature?

    Homework Statement :[/B]Use the energy balance equations you wrote down for the ground layer, the atmospheric layer, and the above the atmosphere layer (space) in part (a) to show that the ground temperature Tg can be expressed in terms of the emission temperature TE as follows: $$ T_g =...
  47. I

    Earth's Energy Balance: Calculating Albedo, Absorptivity, and Emissivity

    Homework Statement Use the data in the energy balance diagram for the Earth shown below to determine numerical values for α, a and e. Assess your results by comparing them to the commonly used approximations α = 0.3, a = 0 and e = 1. Show your calculations. Homework Equations Look at the the...
  48. F

    Atmospheric air pressure on the human body

    Hello, It is well known that the atmospheric air pressure is significantly strong but our body does not get crushed by it because and equal pressure pushes from the inside our body. That said, does it mean that air can exist and be diffused inside solid organs like the lungs, our heart, etc...
  49. PainterGuy

    Why does atmospheric pressure increase as you go closer to the Earth's surface?

    Hi, The air pressure at the surface is about 1,00,000 N/m2. It means that on average, a virtual column of air one square meter [m2] in cross-section, measured from sea level to the top of the Earth's atmosphere, has a mass of about 10,000 kilograms and weight of about 1,00,000 Newtons. That...
  50. |Glitch|

    Atmospheric Heating from Meteorite Impact

    I am proposing a collision between Earth and the Centaur 10199 Chariklo (a.k.a. 1997 CU26). For the actual collision information I used the "Impact Earth" website from Purdue University. This is the data I used: 10199 Chariklo (a.k.a. 1997 CU26) Diameter: 248 ± 18 km (334 x 266 x 172 km)...
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