Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.
15

It's because gases also diffuse. If you separate two gases of different densities by a horizontal membrane, and then slowly remove the membrane, then the interface will diffuse. You can try this with bromine and air, for example – the bromine will stay at the bottom (easily visible because it's brown) and the air will stay at the top, but the ...


13

The traditional answer basically comes down to the physics concept of adiabatic cooling, a description of which is: - There is less pressure as you go up in the atmosphere (basically due to less air weighing down) - Air takes up more volume at lower pressures - Since there's nothing else to supply the energy needed to expand, the air employs the energy that ...


13

The answer is Volcanos. There might be other inorganic processes capable to produce $\text{CO}_2$, but on Earth, the main inorganic source of $\text{CO}_2$ are volcanoes. In some period of Earth's history, there is evidence of large glaciations events, some of them are thought to have been triggered by the lack of $\text{CO}_2$ (like the Snowball Earth and ...


9

Diamonds are expensive. Really expensive. Even "cheap" synthetic diamonds are orders of magnitude more expensive than conventional fossil fuel. By using them as fuel, you will increase demand, thus increasing their price even more. And synthetic diamonds have to be made somehow, and you need energy for that. Diamonds burn, but they don't burn well. For ...


8

I'm not sure I can give a good technical answer. I don't think the amount of oxygen in the Earth's atmosphere is due to equilibrium but more of a consequence of the formation of the solar system, Earth chemistry and biology. If you look at the formation, for inner planets, much of the gas and ices were blown off due to their inner orbits and the planets ...


8

You are correct in thinking that oxygen comes from photosynthesis. In fact it is so much associated with photosynthesis, as opposed to any inorganic process, that the presence of oxygen in the atmospheric spectrum of other planets (solar or exoplanets) is reckoned to be one of the best indicators of life beyond Earth - not that such oxygen has been ...


8

To my eyes, the belt of Venus looks purple, which didn't makes sense to me, as the very short wavelength of purple light should have been scattered long before arriving back there. Then all made sense when I realized that if you mix blue and red light you get purple. You got that part right. Purple is not violet. Violet is a spectral color at the high ...


7

Another way of looking at the question: I take 2 standard wheelbarrows of bits of plants from my garden. One wheelbarrow is used to fill the compost bin. The other goes to the bonfire. How much ash do I have from burning compared to how much compost from the compost bin. Any gardener will know that the amount of compost will be much larger than the amount ...


7

My guess would be a combination of boundary layer, cloud cover, and emissions (though that isn't terribly specific). Smog is a combination of nitrogen oxides (which cause smog's brown color), ozone, and particulate matter. These in turn form from emissions of hydrocarbons and nitrogen oxides from vehicles and industrial combustion. If those emissions are ...


7

Atmospheric escape is the loss of planetary atmospheric gases to outer space. You'd never be able to contain ALL of any gas forever by gravity. Ultimately you end up in the rarefied atmosphere where there is some probability that a molecule of gas will reach escape velocity. The probability distribution is given by the Maxwell-Boltzmann distribution and the ...


6

I think it is important to keep in mind the mechanisms that form PM$_{2.5}$ are different than the mechanisms that form O$_3$. From the data your provided you can draw some simple conclusions: Increasing SO$_2$ increases PM$_{2.5}$ Increasing NO$_2$ increases PM$_{2.5}$ Increasing NO$_2$ doesn't necessarily increase O$_{3}$ The last point is what you ...


6

Except for Rayleigh scattering (Is the color of the sky the same everywhere on earth?) gases typically do not add any color to atmospheres, they are usually transparent in visible light. The Halogen gases (F$_2$, Cl$_2$,Br$_2$, I$_2$) have color though, and there are a few other colored molecular gases, but you would not expect them in planetary atmospheres. ...


6

As defined in the AMS glossary, a parameterization is a simplification of one or several processes in a model. I add that a parameterization commonly adds an error and increases the uncertainty in the model results. In most cases, a parameterization is not derived from physical laws but a fit to data. These simplifications are employed for different reasons....


6

The difference between advection and convection in Chemistry Transport models (CTMs) is a question of scale: Advection is driven by winds that are provided by the meteorological input dataset. Thus, the wind is resolved in the meteorological data. Convection is driven by sub grid processes (e.g. temperature gradients) and is paramterized in CTMs. See for ...


6

Carbonaceous aerosols are formed by a mixture of substances with different chemical, physical, and optical properties. Certain organic substances are mostly transparent to sunlight and therefore do not contribute to Earth warming or cooling. Other substances are mostly reflective, therefore their presence in the atmosphere contributes to Earth's cooling. ...


5

Background pollution is what would be measured if no anthropogenic emissions existed. In other words, if you shut off human activity (or avoid the emissions from it), you can measure the background. Sometimes this is called the natural background. There are also regional backgrounds, like "the US background", which additionally includes anthropogenic ...


5

The difference is that a carbon sink accumulates carbon, whereas a carbon reservoir has accumulated carbon. That is to say: A carbon sink is an ongoing process which is increasing the amount of carbon stored in it. Whereas although a carbon reservoir might exchange individual carbon-based molecules with other parts of the carbon cycle, as much will go out ...


5

There is no simple relationship since it all depends on the frequency (IR spectral lines for most species of molecules are a mess). The most direct and precise way of calculation is through line-by-line calculation from a large spectrum database. The atmospheric column will be very different based on angle off normal, weather, and even time of day (water ...


5

Let's first consider the scenario in the absence of free radicals that can act as catalysts of $O_3$ destruction. In such scenario, added to the absence of UV radiation, the photolysis of ozone ($O_3 + UV → O_2 + O$) would not be possible. Therefore, the only way to destroy ozone would be by the reaction $O_3 + O· → 2 O_2$ But the lack of UV radiation ...


5

Scientists can measure the chemical composition of the atmosphere of other planets using spectroscopy. Each molecule in the atmosphere absorbs and re-radiates at specific frequencies of light that are a function of temperature and unique to the specific type of molecule. For more information see https://en.wikipedia.org/wiki/Extraterrestrial_atmosphere and ...


4

A carbon reservoir is measured by the amount of carbon it contains, for example kilograms of carbon [kg C]. A carbon source or sink is measured by the amount that comes out or into the reservoir from the rest of the system per unit of time, for example kilograms per day [kg C/day]. A coal or oil deposit can be either a reservoir or source, as carbon flows ...


4

Atmospheric oxygen is not in an equilibrium of 21%, it just changes very slowly. For instance, oxygen has decreased by 0.7% over the past 800 thousand years, likely due to increased erosion (which exposes more rock that can be oxidized) and cooler oceans (which can then absorb more oxygen). So, while it is a slow process on geologic timescales, the amount ...


4

Each one of the monitor siting examples you list has a different purpose. As you have listed, a monitor will be sited for air regulatory compliance purposes (e.g. determining the highest concentrations downwind of a major source), understanding the region (e.g. representative site in well-mixed location), or health exposure risks (e.g. densely populated ...


4

The hydroxyl radical chemistry is not modeled explicitly in air quality models, so numerical stability is not an issue. Instead, OH is held in pseudo-steady-state. For instance, see CMAQ's documentation which states: In CMAQ's gas phase, OH is assumed to be in pseudo-steady state, and it is not a transported species. This is because hydroxyl radical ...


4

Ozone is most closely correlated to temperature. Yes you need NOx and VOCs to create ozone, but you also need enough photolysis driven by sunlight in order for ozone to form. The day analyzed in the question is during the middle of winter, which generally does not have enough sunlight to allow ozone to build up in the atmosphere. Furthermore, when there ...


4

According to the US Carbon Dioxide Information Analysis Center : Though in their data table they use the term "ppmv", they explain: The CO2 mixing ratios are reported as micromoles per mole (µmol/mol = ppmv) of dry air in the World Meteorological Organization (WMO) X85 mole fraction scale, traceable to primary standards at the Scripps Institution of ...


4

Look at the pysolar docs (http://pysolar.readthedocs.io/en/latest/) under "Estimate of clear sky radiation". The algorithm does not return zeros at night, but instead just plugs those numbers straight in, giving nonsensical values. Filter the results so that if altitude_deg < 0, the radiation is 0. An example just using pysolar, datetime, and pyplot (I ...


4

"Is there any interaction between the Earth's atmosphere and high velocity protons in the solar wind (e.g. protons combining with atmospheric oxygen to form hydroxide) which is capable of balancing the hydrogen loss?" I found Hydrogen ions in the solar wind react with oxygen in interplanetary dust grains to form little packets of water, potentially supplying ...


4

Oxidation states of sulphur vary between -2 and +6. Sulphur compounds are generally emitted in reduced form. They are then oxidised in the Earth’s atmosphere, generally to SO2 , a +4 oxidation state. Around 65% (the remainder is removed by dry deposition) of this sulphur dioxide is eventually oxidised to the +6 state of H2SO4 , where SO2 – 4 is ...


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