# Tagged Questions

The study of the composition or dynamics of the gaseous layers around planets, often applied to questions on Earth's atmosphere but can be applicable to all planets & moons in the solar system.

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### Can I launch an object into orbit using only a cannon?

My friends and I were reminiscing about our intro physics classes and decided to revisit an old problem were we were required to calculate the orbital velocity of a cannonball fired from 1 meter above ...
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### What does “downshear” mean?

I occasionally read descriptions such as "downshear of the vortex" in meteorological publications. What does this mean?
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### How Temperature, Pressure and Altitude are related in the atmosphere?

I'm looking for an approximation for the temperature of the atmosphere at any height and pressure. Both altitude and pressure are known variables, I've derived this equation using maxwell's ...
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Adiabatic lapse rate is defined as $$\Gamma_a \equiv -\left(\frac{dT}{dz}\right)_{\rm parcel}=-\frac{R_{\rm a} T}{c_p \,p}\left(\frac{dp}{dz}\right)_{\rm parcel} = \frac{g}{c_p}$$ $R_a$ is gas ...
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### Why do high altitudes have larger diurnal temperature variation than lower altitudes?

It seems like the lack of atmosphere should not be playing a role in the diurnal temperature variation because that's what makes it colder. Mountains are not that dry, usually.
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### If you were able to get rid of Hydrogen from a weather balloon as it were rising and expanding would the weather balloon rise further than usual?

I know that the weather balloon will eventually be stopped because of the atmosphere no longer being buoyant but would the balloon be able to go farther than it regularly would?
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### How much and what kind of sunlight passes through a cloud?

I've read that 80% of sunlight is passing through clouds. Now there a small clouds and big clouds so it should be some average. Is this true or is the amount of sunlight passing throug a cloud really ...
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### How to account for lower tropospheric horizontal refraction

With regards to the lowest 5kms of the troposphere, the International Standard Atmosphere models don't support a notion of a linear increase in air density along Horizontal axes. Yet, the path of ...
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### Diffusion of gases in the atmosphere

Suppose that the atmosphere is composed of 21% $O_2$ and 78% $Kr$ (instead of $N_2$). Since the density of $Kr$ is greater than the density of $O_2$, the lower atmosphere (where we live) should be ...
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### Special conditions at layer F2 ionosphere

I saw this graph about the electrons density in different altitudes and difference between night and day, the difference between the 2 electron densities (day and night) decreases till 300 Km (F2 ...
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### How to correctly calculate the colour of the sky?

It is well-known that the sky is blue due to Rayleigh-scattering. What bothers me though is the question how to actually calculate the spectrum of the scattered sunlight. Yes, use one of the ...
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### Behaviour of Altimeter at different temperatures

I have realized that the Altimeter of my bike computer (it uses Air Pressure to determine altitude and needs to be calibrated every start) is not consistent at different temperatures. At the Start ...
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### Ionospheric electron density measurements

I've been working on measuring total electron column density (TEC) with multi frequency GPS data. In theory, signal delay caused by TEC differences should affect the code and carrier nearly evenly in ...
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### False sunset and false sunrise time estimation

False sunset and false sunrise are described . Here is a sample day rise and set time according to AccuWheather site and calculated value of sunrise and sunset in my country. Could you please help ...
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### Bulk and dynamic viscosity in the atmosphere

I'm studying the physics of the atmosphere but I'm struggling with the matter of viscosity (Navier-Stokes equation) for gravito-acoustic waves. From Landau-Lifschitz :  (T)_{ij} = -p\delta_{ij} + \...
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### Mathematical approaches to atmospheric refraction

Understanding atmospheric refraction, particularly of ultraviolet, and into the blue part of the visible spectrum is of great interest to me. Although, I have a strong background in trigonometry and ...
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### What is the mean ionospheric height?

I am reading some articles about the ionosphere and I am a little bit confused about the terms mean ionospheric height and effective height of the ionosphere. Are these the same thing? I would ...
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### seemingly impossible query

While on an expedition to a lake, it was noticed that the wind speeds gusted violently in seemingly periodic wakes and the proposed explanation was Von Karman vortex shedding off of nearby mountains ...
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### Surface UV exposure with cooler star

If the sun's surface was ~ 4000K (and earth closer to compensate), the UV component of the radiation would be less. However, UV makes ozone via photolysis of oxygen. Also, the stratosphere would ...
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### Velocity Profile of the Upper Atmosphere

Consider an Earth-Centered Inertial (ECI) frame in which the tangential (to Earth's surface) velocity is measured. Now consider obtaining constant average velocity profiles of the atmosphere as a ...
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### Is there a resonance within the earth, separate from the Schuman resonance?

In a very recent biography of Nikola Tesla by Bernard Carlson, the author explains that Tesla measured the resonant frequency of the earth using his invention - the amplifying transmitter. Tesla came ...
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### What instruments are used to determine the degree of water in the atmosphere of Mars?

More precisely, how does one go about measuring the small amount of water vapor in what is almost a vacuum by terrestrial standards?
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### How can a gas giant be said to have an atmosphere?

They are made of gas, right? So, there won't be a solid-gas or liquid-gas boundary that defines where the atmosphere starts. So, if there isn't a boundary, we can't define part of it to be an ...
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### How is convection possible in fluids, in the absence of a contact surface for any buoyant force?

I don't understand why liquids and gases are acted upon by a buoyant force. In a solid immersed on some fluid medium, the pressure pressure difference caused by gravity exerts a force on the surface ...
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### How far we can see in the thickest possible fog?

There is quite foggy day today here, I cannot see end of the street. This made me think about how much worse can it be. So here is my question: how thick a fog can be? What's the smallest visibility ...
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### Generic Rayleigh effect experiment - nothing happens for water

On youtube, a bunch of Rayleigh scattering experiments (e.g this one are set up with some compound being added to water in order to invoke the effect. Why is there no Rayleigh effect for "pure" water?...
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### Maximum temperature possible on earth

What is maximum temperature that can we have on earth on a single day? Lets say an air mass is static over an area and there is no way for air mass to move, sun warming it up would increase ...
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### What is wind chill a function of?

When the weather report includes a wind chill, was that value experimentally determined by sampling the conditions on the day of the report? Or was it calculated from other data? If so, what do you ...
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### Atmospheric Tides effect on atmospheric pressure

Regarding the atmospheric tides effect on the pressure, this answer (and the referenced sources) seem to point that such effect is very small. However, this pressure prediction graph for my hometown ...
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### Modeling atmospheric reentry with respect to the rotation of a planet and its atmosphere in a simulation

I am creating a hard science fiction flight simulator. I am a civil engineering student, so its a little out of my area of study. Currently I model air resistance on the velocity difference between ...
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### Global Circulation Model of tidally locked planets for PC?

Is there some free simple Global Circulation Model that can handle tidally locked planets and can be easily compiled and used on a PC computer? It does not have to be very precise, I am interested ...
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### Which is the most accurate way to model the fundamental atmospheric parameters of the Earth?

I need to calculate the fundamental atmospheric parameters, I mean the actual ones, this is not an exercise but a model for a real world application so I need to take account of the humidity of air. I ...
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### What kinds of reactions happen when bubbling air through water?

Mostly I have seen air bubbling used to remove impurities in the water itself, like exemplified in this course packet. This is called "Sparging," but I have yet to learn much about transfer between ...
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### virtual air-surface temperature difference above a water body

I'm trying to work through the equations for the following paper: http://onlinelibrary.wiley.com/doi/10.1029/2009JD012839/abstract and am trying to understand the concept of virtual air temperature, ...
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### What is the relationship between atmospheric refraction and path curvature?

Light traveling in a "curved" trajectory suggests a linear increase of the refractive index over the entire distance (uninterrupted super-refraction). A lapse in the increase of the refractive index ...
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### Clarification regarding atmospheric opacity

I have taken a look at the related questions Can someone explain to me the concept of atmosphere opacity? and Why can spacecraft observe terrestrial gamma rays, but terrestrial observers not ...
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### Ultra-cold gas giant atmospheres

In the troposphere, which has the bulk of the atmospheric mass, it's colder at higher altitudes due to adiabatic lapse. Gas giants have several different chemicals that condense into cloud decks at ...
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### If Earth's atmosphere would be cooled, how would its pressure change relative to its temperature?

I have a feeling it would not behave like an ideal gas? For example, if the atmosphere were to cool down at a constant 1 atm to 90 K, oxygen would liquefy. If changing of pressure would be considered,...
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### From coriolis force, cyclone goes wrong direction

note, comment below (BowlOfRed) asked for more detail, so this is more a re-write than an edit. In an idealised weather system, there can be a high pressure area, and a low pressure, and air goes ...
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### How much pressure would be on Mars if the icecaps melted?

I was wondering, The martian polar ice caps are made of water and CO2. All documentaries say that melting the poles can add pressure. How much pressure would there be? I know that every summer they ...
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### Covering the whole world in an EMP

I recently thought about shutting down the whole worlds electronics, and naturally ended up with an EMP. I know that EMPs are generated when nuclear bombs explode, but nuclear bombs have some unwanted ...
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### Calculating accuracy, error, full scale error, relative error and more in a specific case

I recently bought a O2(oxygen) sensor and I am trying to figure out the error in the percentage O2 (O2pct, unitless but in %) output value that it gives out. This error is not stated in its data ...
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### How long does it take for an Oxygen to diffuse around Earth?

We drill into the ground and find a huge pocket of oxygen. How long does it take for that oxygen to diffuse around Earth? I'd like to know for the first oxygen molecule how long it takes to effect the ...
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### Altitude altimeter application

What is the most precise formula to calculate altitude and what parameters should i considet such as pressure, temperature, dew point, ... I am developing an altimeter app and i don't know what the ...
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### How much of the sunshine is scattered into the space?

How much more sunshine will the earth ground receive if without the atmosphere?
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### Explanation for strange atmospheric phenomenon

OK, I've seen this strange thing in the sky sometimes. Not all that often, but sometimes. It actually happened tonight. On most nights, at say 9 P.M. it is dark. There might be stars, moon, etc.,...
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### Difference between mixing ratio and mole fraction

I have been reading 'The Atmosphere of Venus' by V.I. Moroz which is available here. I am confused about the term 'mixing ratio' which is used on discussions in chemical composition. From what I ...
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### Calculating saturation mixing ratio for water in air

If I have air pressure (in, say, Pa) and air temperature (in, say, K) - how do I calculate the saturation mixing ratio for water? I can't seem to find it anywhere and it's a fairly useful quantity to ...