Questions tagged [atmospheric-circulation]

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What does the "strength" of a circulation cell refer to?

I'm reading articles about climate models for possible exoplanets, and I'm confused as to what the "strength" of a Hadley or Ferrell cell refers to. Does it refer to wind speed? Wind force?
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18 views

Compute upwind flux for gridded data

I'm trying to compute something called the "Drying Ratio" following: Eidhammer, 2018 The drying ratio is the ratio of the precipitation to the incoming vapor flux. So, $DR = \frac{F_{in} - ...
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3 votes
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33 views

Why does cloud cover seem to "ride" a wave that propagates westward near the equator in this video?

https://www.youtube.com/watch?v=wVRbeGc_6zM Notice that the cloud cover over Africa and South America is correlated in a way that seems to be highlighting some kind of large-scale easterly wave ...
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6 votes
2 answers
166 views

How do academics/institutions run large climate simulations given the computing challenges?

I have been brushing up on numerical methods for PDEs lately, and climate models provide such a rich set of models and ideas to practice with. However, I was a little confused about how academics can ...
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1 answer
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How to derive the total potential energy of the atmosphere?

In one of Lorenz’s paper (I mean the meteorologists Edward Lorenz), he stated that the total potential energy of the whole atmosphere $P + I$ (means the sum of potential energy and internal energy) is ...
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1 answer
66 views

Vertical air speed

Assuming that the divergence varies linearly with the pressure between the surface (1000 hPa) and the tropopause (200 hPa). Can someone tell me how do we calculate the vertical speed on the pressure ...
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1 vote
2 answers
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How to search for the nearest non nan value in 2d xarray dataset

I have a 2d xarray dataset and I am having several nan values in the dataset. These nan values need to be filled with the nearest non-nan values in the 2d array. How do I do this? I am trying to ...
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3 votes
1 answer
996 views

Why is the pressure on the poles higher in Summer and lower in Winter?

Just to give context, this was not my original question but one that I ended up stuck with while trying to find a cause for the following observation (which is almost universally true for temperate ...
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4 votes
2 answers
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How to install ESMF and ESMFPy in Ubuntu using gfortran, gcc, python?

I am trying to regrid some of my latitude-longitude grid files to tripolar ocean grid and found that ESMF can be useful. However, I am finding it hard to install the same.
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3 votes
1 answer
223 views

How to convert the units of specific cloud liquid water from ERA5 (kg/kg) to kg/m2?

I am trying to initialize my model with the cloud liquid water data from ERA5. My model IITM-ESM which evolved from CFSv2 takes in the cloud liquid water information in $\small\mathsf{kg/m^2}$. ...
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7 votes
1 answer
154 views

Can we see the circulation cells in wind maps?

Earth famously possesses three distinct circulation cells per hemisphere. Now out of curiosity one could use a weather app, like windy, to display the wind structures at ground level globally, and ...
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3 votes
0 answers
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Application of vorticity tendency equation

I have a question about the dynamics of westward propagating vortices. In meteorology, the vorticity tendency is often used to explain the westward propagation of vortices (cyclonic circulation). A ...
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Initiation of Rossby waves during MJO

I am trying to understand the basic dynamics of MJO, where I find several studies which relate it to the initiation of equatorial Rossby and Kelvin waves. Though MJO is an eastward propagating wave, I ...
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3 votes
3 answers
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Temperature Advection using finite differences with gridded data

Advection of a scalar quantity, such as temperature (T), by the horizontal wind, is defined as follows: $-\textbf{U}\cdot\nabla T$ where $\textbf{U}$ is the horizontal wind vector, $\textbf{U}=(u,v)$...
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4 votes
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For fine particles to get dispersed throughout the globe via atmospheric circulation, in what level of the atmosphere would they have to travel?

For molecular-sized particles to disperse around the entire planet, would they have to reach the stratosphere, or could air currents in the troposphere distribute them? Are particles dispersed ...
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3 votes
0 answers
127 views

Internal energy, enthalpy, and work in the atmosphere

I'm writing a toy radiative-convective atmospheric model and need to relate the heat flux convergences (either surface sensible heat flux or the radiative flux) to changes in atmospheric layer ...
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17 votes
2 answers
19k views

Why are deserts mostly located on the western side of continents?

I read somewhere in a book that mostly desert found in the western part of a continent. So my question is that why is it so? I searched on the internet but I didn't get a reasonable answer for that.
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3 votes
2 answers
369 views

Latent heat and global circulation

What is the relation of latent heating and the global circulation of the atmosphere? Do you know some references about this relationship?
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11 votes
2 answers
5k views

Why is Egypt so dry?

If you look at this wind map (for July, but following the link you can also view other months): you will see that Egypt gets its air from the Mediterranean sea. During other months it could get less ...
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1 vote
0 answers
217 views

Buoyancy frequency

The buoyancy frequency, $N$ is defined as $N^2=\frac{gd\theta}{\theta dz}$, where $\theta$ is the potential temperature (I see it as a measure of the deviation from the adiabatic nature), $z$ is the ...
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6 votes
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Forced shallow-water equation with diabatic heating as the source term

How to obtain the divergence of velocity field $\left(\nabla.\mathbf{u}\right)$ with ${Q}$ (something proportional to the diabatic heating rate) as the source term from the thermodynamic equation? ...
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5 votes
0 answers
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Physics based circulation models

How useful are physics based models when considering circulations at synoptic scales? Are they useful? Can we not make predictions, observe trends based on data alone? I am studying A.E.Gill's model ...
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4 votes
2 answers
298 views

How is there enough $\ce{O2}$ in the atmosphere to breathe if you are in a desert with no plants?

Humans depend on $\ce{O2}$ for breathing. The source of $\ce{O2}$ is photosynthesis by plants or cyanobacteria in the ocean. How is it, that when people travel through deserts or the Arctic / ...
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7 votes
1 answer
1k views

Why do the dry and moist adiabatic lapse rates converge with height?

Near the surface, the slope of the moist adiabats are much steeper than dry adiabats due (as I understand it) to the the latent heat released as water vapour condenses. The difference is amplified at ...
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12 votes
1 answer
468 views

Relation between direction of shear and tropical cyclone formation

In an earlier question/answer Why are there no cyclones in the southern Atlantic basin there was a point raised about direction of shear(abetting/retarding) cyclone formation. It appears ...
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9 votes
1 answer
238 views

Monsoonal interactions with mid latitude disturbances

For the past few years in succession India has witnessed extreme flooding events caused by monsoonal troughs colloding with what appears transitory mid latitude disturbances and these appear to ...
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3 votes
3 answers
181 views

Is everything affecting everything on Earth?

If a single butterfly can alter the future, then can't every single action keep the future in chaos? According to the question about butterfly effects, this must be so, is it not? If this is an ...
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14 votes
1 answer
1k views

How long does it take for the atmosphere to mix?

If I release a say, one litre of gas, at a particular point on the planet, how soon, on average, would it take to be distributed evenly (mixed) across the entire earth's atmosphere?
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33 votes
1 answer
4k views

What factors determine the number of Hadley cells for a planet?

We know (think?) that Earth has three Hadley cells per hemisphere, but from observing gas giants such as Jupiter, we see that they have many more cells. According to a link from a comment in this ...
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26 votes
0 answers
498 views

Is it possible for a sting jet to form over a continental landmass?

Sting jets are thought to be responsible for some of the most damaging winds associated with extratropical cyclones in the mid-latitudes. So far they have only been confirmed in the European region, ...
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18 votes
2 answers
7k views

Why does the Hadley cell descend at 30 degrees?

George Hadley's initial model of the Hadley cell described air as being heated at the equator, ascending, and then moving aloft pole-wards where it would cool and descend. Meanwhile surface air would ...
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16 votes
2 answers
2k views

Why does the El Niño Stop?

The reason for the initiation of the El Niño is unknown, but what is well known is how it progresses once initiated. The West Pacific warm pool begins to drift East, and the strength of the trade ...
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11 votes
1 answer
1k views

Why does the meandering pattern of the jet stream itself propagate?

It is well known that the jet stream follows an overall meandering pattern, but what is less well known is that this meandering pattern itself moves as a wave with a velocity much slower than the ...
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