Questions tagged [atmospheric-chemistry]

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16
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2answers
2k views

How is the equilibrium of 21% oxygen in Earth's atmosphere established?

The atmosphere is 21% oxygen. I assume that there must be an equilibrium between processes that produce oxygen (e.g. photosynthesis) and those that consume oxygen (e.g. aerobic respiration). Moreover,...
11
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2answers
198 views

How did CO₂ originate on Earth before there was life?

To start life there has to be $\ce{CO2}$. $\ce{Solar energy + 6CO2 + 6H2O -> C6H12O6 (sugars) + 6O2}$ $C_6H_{12}O_{6} + O_2 \longrightarrow H_2O + {CO}_2 + \text{Energy}$ So to start this cycle, ...
10
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2answers
2k views

What keeps the different gases mixed in the atmosphere?

Consider a gas centrifuge holding two different gases. After spinning for a while, the heavier gas will move to the outside, and the lighter gas will be on the inside. In other words, we have ...
10
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1answer
1k views

Does natural plant decomposition release more greenhouse gases than burning

I understand that all plant matter releases CO2 as it decomposes and also when it burns in, for example, a forest fire. My assumption, upon which this question is based, is that the CO2 release is the ...
10
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2answers
165 views

A rough picture about the ground-level ammonia (NH3)

Ammonia is the only alkaline gas in the atmosphere. It is one of the key features to control the acidity of aerosols and the formation of ammonium salts. In the environment of $NH_3$-rich and $NH_3$-...
10
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1answer
245 views

What principles do we consider when selecting an air pollution monitor location?

I'm working on a project aiming at finding some potential point as a new air pollutant monitor site for a city to measure $SO_2$, $NO_2$, $PM_{2.5}$, etc. After modeling the surface concentration of ...
8
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1answer
1k views

What's the background concentration of trace gas/pollutants?

I have read a paper discussing the concentration of air pollutants and their background concentration. In the paper Characterization of background air pollution exposure in urban environments using a ...
8
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3answers
5k views

ppmV versus μmol/mol for atmospheric CO2 - how to convert?

For a uniform mixture of ideal gases, I think that the concentration of a gas reported in parts per million by volume (ppmV) and micro-moles per mole (μmol/mol) would be the same. When I see ...
7
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1answer
850 views

Why is it colder in the mountains than at sea level?

I have heard numerous reasons why that is. I just want to know which one is right.
7
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1answer
259 views

Why is the Earth's shadow blue?

After every sunset, once the sun is gone, I always enjoy seen the belt of venus rising in the other side, followed by the Earth's shadow. This is a picture I took (you will find better ones online). ...
7
votes
1answer
412 views

What “g” would be needed to keep helium on Earth?

I know that helium is a very light and rare gas on Earth because Earths gravity is not strong enough to keep it. Instead, helium and hydrogen are rising through the atmosphere and escape into outer ...
7
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1answer
999 views

What causes smog to clear up on some days?

I notice that in my town sometimes the pollution/haze/smog sticks around on some days but then on others the sky can be completely clear. I don't necessarily see any difference between windy and non ...
7
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1answer
163 views

Persistence time of ozone

Ozone is formed in the upper atmosphere by ultraviolet light, and broken down by ultraviolet, spontaneous reactions and artificial pollutants among other things. Suppose there were no artificial ...
7
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1answer
121 views

What causes the semi-annual mesospheric meteoric potassium variability?

In a recent study presented in the article First global observations of the mesospheric potassium layer (Dawkins et al. 2014), space-borne resonance fluorescence observations confirmed previous LIDAR ...
7
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1answer
159 views

Is there an atmospheric hydrogen cycle?

There are various physical, chemical and biological processes that free up hydrogen from molecules (often hydrocarbons or water). Once in the atmosphere, the hydrogen is lost to space (the Earth's ...
7
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1answer
67 views

How to relate the backward trajectories with offline particular samples?

To correlate chemicals in aerosols emanating from certain sample points, backward trajectory analysis is usually applied for identifying the potential geographical source region. In this figure ...
6
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2answers
198 views

How to understand the bizarre high level for both PM2.5 and Ozone

Background Eastern China now (2017.01) are suffering severe haze with striking concentration of PM2.5. Haze, with low visibility and complex chemical components threatens billions of persons' health. ...
6
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2answers
82 views

Does hydroxyl radical chemistry in air quality models create numerical stability problems?

Atmospheric mixing ratios of the hydroxyl radical have relatively short lifespans (on the order of microseconds). When modeling air quality or the weather, the time step is usually much larger than ...
6
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1answer
100 views

What is brown carbon?

There is a lot of interest in brown carbon in the atmospheric science community these days. There is a paper in the journal, "Atmospheric Chemistry and Physics" titled, "Black carbon or brown carbon? ...
6
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1answer
365 views

The difference of vertical advection and convection process for chemistry species

In atmospheric, the change of mixing ration $C_i$ of a chemical species $i$ is determined by: $\frac{\partial C_i }{\partial t} = -\bigtriangledown (VC_i)+\frac{\partial }{\partial z}(k_z\...
6
votes
1answer
95 views

What is the ratio of infra-red light absorbed by green house gases?

I know that some gases like CO2, N2O and CH4 absorb infra red radiation. What is the proportion or percentage of radiation absorbed by CO2 among all the gases?
6
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2answers
4k views

Is oxygen spread equally on Earth's surface?

We know that oxygen comes from trees and plants (photosynthesis), so in the jungle where there are a lot of trees you would expect more oxygen than in the desert where there are no trees. Walking in ...
5
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3answers
12k views

What is the difference between a carbon sink and a carbon reservoir?

I am trying to figure out the difference between a carbon sink and a carbon reservoir. The definition for a carbon sink from wikipedia is that “carbon sink is a natural or artificial reservoir that ...
5
votes
1answer
177 views

What would a planet's sky look like with different chemical compositions, such as low nitrogen, high methane etc?

What are the processes, chemicals and particles involved in creating colour in a planet's sky? Could you give some examples of sky colour processes different from what happens on Earth?
5
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1answer
80 views

What controls the tendency of trace elements in different particle size fractions?

Trace element atmospheric particles are introduced from different sources, with both anthropogenic and natural origins. By analyzing the concentration levels of 18 elements in samples of $PM_{2.5}$ ...
5
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0answers
96 views

Dig in the rationality of model evaluation of WRF with land-based station data

I use WRF (Weather research and forecasting) model for in regional scale meteorology simulation. And then, the WRF output files will be deemed as criterial input data applying for chemical transport ...
4
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2answers
331 views

Can I use diamonds as fossil fuel?

Aside from cultural implications (correct me if I'm wrong but artificial diamonds are not so hard to obtain, right?) diamonds are pure carbon and are more unstable than graphite. So, why not use ...
4
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1answer
203 views

How can scientists measure chemical composition on other planets?

How can scientists measure chemical composition (oxygen, nitrogen etc) and temperature on other planets without being there?
4
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2answers
247 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 / ...
4
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1answer
304 views

What is principle of inverse modeling?

I read a few paper related to emission inventory talking about the inverse modeling. It was another method to estimate the emission from ground(called top-down ...
4
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1answer
47 views

What exactly are “ambient aerosols”?

I see this term being used everywhere, but I have not been able to find a formal definition for "ambient aerosols".
4
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1answer
69 views

The higher value range for the same satellite product (NO2_OMI_TEMIS)

I'm dealing with NO2 column density of troposphere, and my data source is TEMIS. The NO2 level3 data can be derived from the original information of OMI instrument. I have downloaded two types of ...
4
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0answers
61 views

How is the vertical distribution of water vapor changing?

In this publication about data assimilation and observations (paywall alert) in the chapter General Concepts in Meteorology and Dynamics (by Andrew Charlton-Perez, William Lahoz, Richard Swinbank, ...
4
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0answers
58 views

What are the benefits of direct sun viewing spectrometer over a backscatter measuring spectrometer to quantify trace gases in the atmosphere?

I am using a Pandora spectrometer and a MAX-DOAS spectrometer to quantify the amount of formaldehyde (HCHO) present in the troposphere and stratosphere in Fairbanks, Alaska. Both the spectrometers use ...
4
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0answers
96 views

What are 'sulphate particles' in the context of atmospheric chemistry?

This informative answer describes some processes in atmospheric chemistry and mentions "sulphate particles". Actually I realize that I don't know what a 'sulphate particle' really is, though I've ...
4
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0answers
230 views

How to transform the inventory data from degrees to kilometers

First all, my question was different from the question Converting grid resolution from degrees to kilometers. In chemical transport modeling, the pollutant source inventory was an essential input ...
3
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1answer
395 views

The free oxygen (O$_2$) in the atmosphere is largely a result of what process?

Does it come from a)atmospheric lightning and ozone dissociation. b)meteorite impacts early in the earth's geological history. c)Paleozoic volcanic activity. d)photosynthetic processes. e)...
3
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1answer
100 views

What denotes a parameterization in a model? (semantics )

I know that WRF has many different uses and options, from atmospheric chemistry to uses with fires, and so on. What exactly denotes a parameterization? For example, in WRF-Chem, is the chemistry ...
3
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1answer
550 views

How to calculate the solar radiation at any place, any time

The solar radiation is one of the important factors controlling the formation of $O_3$, and thereby impacting the levels of various secondary species in the atmosphere. However, in the campaign of ...
3
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1answer
65 views

The influence of special emissions (possibly coal mining activity) on particulate matters

Based on multiple site sampling of airborne $PM_{2.5}$ and $PM_{10}$ , the elemental concentrations of the trace elements were analyzed. I have found out in the site near surface coal mining zone ...
3
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1answer
91 views

What control the atmospheric lifetime of different metals in aerosols?

Background I'm analysing the metallic elements in $PM_{2.5}$ to identify their possible anthropogenic sources for the study area. A total of 19 metallic elements were investigated including dust-...
3
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1answer
75 views

How would this experiment's different particle types produce atmospheric reflectivity?

The MIT Technology Review news item Harvard Scientists Moving Ahead on Plans for Atmospheric Geoengineering Experiments discusses a proposed experiment to study in a carefully controlled way the ...
3
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0answers
161 views

Where does molecular hydrogen in the atmosphere come from?

This figure from Wikipedia's Atmosphere of Earth shows a hydrogen fraction of 0.000055 percent by volume. Question: Where does molecular hydrogen in the atmosphere come from? Does this come directly ...
3
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0answers
65 views

Do NO2 and O3 titrate each other out in the atmosphere?

Here is a plot of the vertical column densities of NO2 and O3 from an ultraviolet-visible spectrometer in Fairbanks, Alaska. It is interesting to see that when NO2 dips, O3 rises, and vice versa. Also,...
3
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0answers
87 views

The factors should be considered to determine one specific pollutant originated from regional transportation?

Ideally, one pollutant (e.g. organic carbon, heavy metals, sulfate) should be the mixed result of local emissions and regional transportation. To quantify the contribution of local emissions is of ...
3
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0answers
83 views

What geographical areas are NOx sensitive/limited (with regard to ozone)?

Have there been any air quality modeling studies regarding the locations where ozone is considered "NOx limited" (increasing NOx increases ozone) or "NOx sensitive" (decreasing NOx increases ozone)? ...
3
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0answers
91 views

Correlation analysis with primary air pollutants and secondary formed ozone

The Ph.D dissertation Assessment of air quality in Northern China by using the COSMO-ART model in conjunction with satellite and ground-based data which was written by Stefanie Schrader in KIT German....
2
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1answer
36 views

Origin of Sulphuric Acid in the Atmosphere

I often see claims that volcanic emissions of sulphur dioxide, on Earth and on the planet Venus, creates sulphuric acid when it combines with water vapour. It doesn't. Sulphur dioxide creates ...
2
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2answers
111 views

What is the history of atmospheric O₂ concentration?

(This is about O₂, not CO₂) How did the concentration of oxygen change? Over geologic time frames since plants began to produce it, and during the time since the carbon dioxide increase caused by ...
2
votes
1answer
118 views

Stratosphere height vs. Temperature based on ozone concentration

Why does temperature increase as height increases in the stratosphere (15 km - 60 km above earth), when the ozone molecules are most concentrated at about 25 km?