All Questions
1,323 questions
3
votes
1
answer
49
views
Tholins color and scattering
One of the prevailing explanations for the reddish color of certain asteroids surfaces and planetary atmospheres, such as Jupiter's and Titan's, is the presence of complex polymeric molecules called ...
- 357
2
votes
1
answer
107
views
When light is scattered, How do particles in sky decide which frequency to vibrate at?
I understand that when electromagnetic waves from sun hit/interact with the particles(charges) in the sky, the particles also oscillate with the same frequency of sunlight and hence radiate(scatter) ...
- 1,306
13
votes
4
answers
2k
views
Planetary atmosphere interfacing with near vacuum - now put it in a jar
Celestial bodies that have atmospheres have a gravity sufficient to hold the atmosphere to the body. This atmosphere interfaces with the near vacuum of space yet is held to the body by gravity.
I was ...
- 137
1
vote
1
answer
229
views
Clausius-Clapeyron relation for high pressures
I can see that the Clausius-Clapeyron relation depends on the change in specific volume $\Delta v = v_g (1 - \frac{v_c}{v_g}) = v_g - v_c$, with $v_c$ equal to the volume of the condensed phase and $...
- 357
4
votes
2
answers
541
views
Have rocket float into upper atmosphere via balloon [duplicate]
I'm assuming a majority of the fuel used in a rocket to say get to the moon is involved in escaping earth's gravity.
So why can't we create a smaller weighing rocket, with less fuel to carry and ...
- 137
1
vote
2
answers
41
views
Atmospheric pressure in non-nertial frame?
Any object kept in an accelerating container of water feels different pressure than unaccelerated. Because if we go into the frame of water the g effective changes. Since air is also a fluid, a ...
- 36
1
vote
0
answers
18
views
Convection in stratified atmosphere
In the stability analysis of stratified atmosphere in the presence of gravity, we consider a blob of atmosphere and perturb it (move it up by a small height $\Delta z$). Initially, the blob had the ...
- 113
1
vote
1
answer
47
views
Can a cold gas be considered as ideal at a very high speed?
Considering a plane flying in the atmosphere, my book uses the perfect gas law $pV=n\bar RT$. Yet, as the plane itself is taken as the reference, the air ($T=-50°C$) has a speed of $800 \ \mathrm{km/h}...
user343933
1
vote
1
answer
487
views
How do you calculate light attenuation by wavelength at a given air mass coefficient?
I am trying to get a good view of light wavelength distribution as a function of viewing angle, with a specific interest as $z \approx 90^\circ$ near the horizon (sunrise/sunset). Air mass ...
- 133
1
vote
0
answers
23
views
Oxygen condensation on Earth
I am getting interesting results using the Clausius-Clapeyron relation to calculate the saturation vapour pressure of diatomic oxygen. I am using the following values:
214kJ/kg for latent heat of ...
- 357
2
votes
1
answer
731
views
Moist adiabatic lapse rate
Wikipedia gives the following equation to calculate the moist adiabatic lapse rate $\Gamma_w$, assuming that there is only one condensible gas (water vapour) mixed in the "dry air":
$\...
- 357
1
vote
1
answer
48
views
How does a volcanic eruption cool the planet's surface?
For example, after the eruption of Mt. Pinatubo in 1991 according to this paper,
The introduction of large amounts of sulphuric acid aerosol into the stratosphere increases the planetary albedo (...
- 129
0
votes
1
answer
197
views
Calculating pressure in high/low pressure systems
I don't understand how to calculate the surface pressure in high/low pressure systems. For example, let's say we have a planet without oceans whose surface is completely flat. Then at every point of ...
- 357
1
vote
0
answers
60
views
What is the temperature of a greenhouse gas?
The temperature of a gas is usually the sum of the kinetic energy of its particles, right?
Whereas the temperature of a solid object is given by the Stefan-Bolzmann equation, as a function of how much ...
21
votes
3
answers
3k
views
What causes wind gusts?
A difference in temperature causes different pressures, air travel from high to low pressure, and that is wind.
We can even produce wind in an experiment like in this video. In this video, what is the ...
- 730
2
votes
1
answer
67
views
How has Earth's atmospheric water been in previous eras and periods?
How has partial pressure and net amount of water vapor and colloidal water been in previous eras and periods on Earth?
- 966
4
votes
2
answers
424
views
Can low lying clouds increase the distance of the radar reach from 18 to 120 km?
I have seen an article (sorry its Russian) claiming that low lying clouds have increased the distance of the radar reach from the normal 18 km till as far as 120 km. This allowed the military ship to ...
- 409
1
vote
1
answer
236
views
Why is the lightning waveform modelled by double exponential waveform?
As per wiki: The electric current within a typical negative CG lightning discharge rises very quickly to its peak value in 1–10 microseconds, then decays more slowly over 50–200 microseconds.
Why ...
0
votes
2
answers
51
views
How much $\rm CO_2$ stays in the troposphere?
I'm trying to make a model which gives the increase of $\rm CO_2$ in ppm for one year, when given the $\rm CO_2$ emitted in one year.
For now, I've calculated the mass of the troposphere using the ...
3
votes
1
answer
68
views
At high altitudes, does reentry cause the atmosphere to burn, or only heat up?
A Google search reveals the following about high altitude reentry:
A re-entering vehicle develops a very energetic pressure wave at its leading surfaces. The energy density is sufficient to cause ...
- 158
3
votes
1
answer
112
views
How does absorbing a free thermal neutron convert nitrogen-14 into carbon-14? (Radiocarbon dating, etc.)
Why doesn't a nuclide of N-14 simply absorb the neutron created by cosmic rays or solar wind interacting with the atmosphere and become N-15, which is stable?
How or why does the resulting Nitrogen-15 ...
- 4,709
0
votes
3
answers
587
views
Would Aeroplanes or Helicopters work on our Moon?
Would Aeroplanes or Helicopters work on our Moon?
In general , I think , in Aeroplane Case:
(1) Air is required for Aeroplanes to float : Would Moon have enough air?
(2) High speed is required for ...
- 548
0
votes
1
answer
126
views
Where can I find datasets for all confirmed exoplanets, terrestrial exoplanets, and Super-Earth exoplanets?
"The NASA Exoplanet Archive" (https://exoplanetarchive.ipac.caltech.edu/) implies that there are 5,197 confirmed exoplanets. The "5,197 Confirmed Planets 11/02/2022" link leads to ...
1
vote
2
answers
104
views
How can the cooling of Venus near the surface be explained during the time that the specific heat capacity of $\rm CO_2$ quadruples from 60 - 40⁰ C?
Imagine that a planet like Venus with an $\rm CO_2$ atmosphere of 92 bar near the surface could be cooled by shading it from the Sun.
The total heat content of the atmosphere with the initial 464⁰ C ...
- 444
0
votes
0
answers
222
views
Atmospheric friction
So when you lift an object, atmosphere spills in from the sides to fill the empty space. That would mean that the atmosphere is pushing up against the side of the object. So wouldn't that mean that ...
1
vote
1
answer
177
views
Is the atmospheric voltage gradients beneath overcast sky higher or lower than it is on a clear day?
According to Wikipedia and other sources the atmospheric electric voltage gradient near the Earth's surface is approx 100 V/m on a 'fair weather' sort of day. Does a diffusely overcast and cloudy sky ...
- 57
0
votes
1
answer
27
views
Within close proximity, how much does the atmosphere influence light and thus what we see?
Not sure if this is the best place to ask. Apologies if not.
(Assume this is under generally average conditions)
Say you have an object that is 1 metre in front of you. When you see that object, how ...
2
votes
1
answer
172
views
How distant is the horizon on Venus?
Strong atmospheric refraction can make the horizon on Venus much closer than expected, but how close is it? My naive calculation is very different from reported observations.
A source cited in How ...
- 13.2k
0
votes
2
answers
228
views
How does the adiabatic coefficient $γ$ vary with temperature (200K-20000K)? [closed]
At high temperatures, such as those encountered in hypersonic flight, γ varies a lot. My problem is that I can‘t find a graph accompanied by an explanation as to how & why it changes under ...
2
votes
1
answer
119
views
Does pressure decay exponentially for a mixture of gases?
According to this answer, the partial pressure of a gas decreases exponentially in height, when placed in gravity. For a mixture of gases, the partial pressures of each component follows this law ...
0
votes
0
answers
316
views
How much UVA and UVB is blocked by shadow or being indoors?
I could not find a clear answer online so I though to try this forum instead.
I did find answers on how different types of glass can block different degrees of UVA and UVB. But I was wondering, if I ...
- 1
0
votes
0
answers
41
views
What would the theoretical barometric pressure be at the bottom of a canyon that is about 15 miles below Earth's surface?
I'm trying to create a fictional world. I am kicking around the idea of supercritical CO2 lifeforms that live at the bottom of some abyss. I read that supercritical CO2 must be at 88F and 72atm.
I am ...
- 1
0
votes
1
answer
95
views
Is atmospheric pressure on an object in vertical plane equal to that of horizontal plane? [duplicate]
Suppose there is a cubic object placed at a surface level. Will the atmospheric pressure exerted on the upper surface of it be equal to that of the pressure exerted on its sides?
As far as I know ...
- 598
-2
votes
1
answer
54
views
Meaning of $\rho_b$ in equation for air density
I looked for an equation for air density in different parts of the atmosphere and found the barometric formula on wikipedia. My only problem is that I don't understand what p_b means in the formula. ...
- 1
0
votes
0
answers
41
views
Winds or waves in specific conditions?
Winds are mainly produced by differences in temperature of the atmosphere and waves are mainly produced by winds.
However, could a rogue planet (without orbiting any star and with a cold core so no ...
- 2,878
0
votes
0
answers
66
views
How much force would the wind of Saturn (1800 Km/hour) exert on my body if i appear on its surface?
Maybe I should have said pressure. I don't know how to measure the exact pressure of the air molecules on my skin, anyways was curious to know this, like what exactly will happen to my body if i ...
- 1
2
votes
1
answer
126
views
Derivation of the exoplanetary flux observed at Earth (solid angle problem)
I'm having issues understanding how Sara Seager, in her book "Exoplanet Atmospheres", determines the solid angle subjected to a detector on Earth. By the figure:
The solid angle was defined ...
- 25
0
votes
1
answer
85
views
Is it possible to determine a moment in time when earth's atmosphere is no longer breathable due to the reduction in atmospheric pressure? [duplicate]
If the universe is expanding, the "pressure" of the "vacuum" in space is decreasing, the earths Atmosphere is expanding, atmospheric pressure is decreasing.
Taking into account: ...
- 17
2
votes
2
answers
168
views
What percentage of sunlight isn't scattered by the atmosphere?
What percentage of sunlight isn't scattered by the atmosphere and instead will arrive at your eyes directly from the sun.
It's been aksed here before but a proper answer hasn't been given.
I was ...
- 3,001
0
votes
1
answer
64
views
Aerostatic force experienced by object due to air
This is an undergrad physics problem, which puzzled me because of the little background provided; see also the comment below by @RC_23.
Problem.
Compute the force exercised by the air to an object ...
- 103
3
votes
2
answers
157
views
Why the sunset is red and a possible experiment?
Before downvoting: I have read some of the answers and will cite them as well.
Not trying to debunk physics or create conspiracies. I love physics but I don't understand it.
Background
This is more or ...
- 71
0
votes
3
answers
124
views
If you decreased the mass of a planet, but kept the mass of the atmosphere the same, would the air density decrease?
So, I know that atmospheric pressure is a result of both the atmospheric mass and the force of gravity acting on it. If you were to decrease a planet's gravity, but keep the atmospheric mass the same, ...
- 111
1
vote
0
answers
30
views
How to obtain exoplanets transmission spectra from JWST's NIRISS data of WASP96?
I was having a look at JWST's NIRISS data of WASP96 (specifically at the x1dints fits file which should be already calibrated). From this, I would like to obtain a result in a fashion similar to the ...
- 69
2
votes
1
answer
287
views
Would a straw work in a completely sealed container?
Let's say you had a hollow metal cube. A hole is drilled through the side, and a straw is put in. The only way for anything to get in or out is through the straw. The container is filled fully with ...
- 23
0
votes
1
answer
132
views
Confusion about the horizontal pressure gradient force being equal to the gradient of the geopotential in pressure coordinates
I see many sources in atmospheric dynamics express the following:
$\frac{1}{\rho}(\nabla p) = \nabla_p \phi$
For example this source equation 10.
The reasoning given is that $\frac{1}{\rho}(\frac{\...
- 246
1
vote
0
answers
35
views
How does the local zenith angle evolve as a function of atmospheric vertical depth?
From Gaisser's Cosmic Rays and Particle Physics (ed. 2016).
I know $\theta$ and I have the vertical depths $X_{v}$. I want to solve for $X$ via a simple trigonometric relation. However, theta evolves ...
- 11
16
votes
4
answers
5k
views
Does dusk really remain for a shorter period of time at the equator?
It is said that the dusk remains for shorter time at equator than the poles. Because, the equator rotates faster than poles. But it is also true that time is the same in every latitude, and if it's ...
- 1,131
1
vote
3
answers
120
views
Atmospheric pressures
In weather issues, High Pressure cells are characterized by warmer air (of lower density). Low pressure cells have colder air (higher density). Any literature search on this leads to the basic PV=nRT, ...
6
votes
2
answers
535
views
How much solar irradiance do clouds block from reaching the Earth's surface?
Consider a fixed point in the Milankovich cycle and the solar cycle, a fixed Earth-Sun distance, and a fixed horizontal location on Earth, and assume that the Sun is at the zenith for that location. ...
- 49.4k
3
votes
1
answer
87
views
How does cosmic rays influence aerosol growth?
I have read about aerosol formation increasing due to ionisation but unable to understand what actually goes into the process? Can someone please explain how cosmic rays help in aerosol formation? ...
