18
votes
What is an "exquisitely rare pollen corona"? How can pollen produce several tight rainbow circles around the Sun, and why pollen specifically?
This is an interesting phenomenon that I haven't seen before. To start off with a discussion of coronas in general, they are fundamentally caused by diffraction, a form of optical scattering where the ...
- 1,144
10
votes
How do current pollution levels in Los Angeles compare to the 1970s?
The air quality in Los Angeles does not meet federal air quality standards. That being said, the air quality has improved immensely since the 1970s.
From the California Air Resource Board, in 1965 ...
- 13.8k
8
votes
Accepted
How is the concentration of particulate matter calculated per cubic meter
The data that you are having are called emission fluxes. If these data are available as global averages then one can calculate global mean concentration by multiplying the residence time of the ...
- 797
8
votes
Accepted
How do current pollution levels in Los Angeles compare to the 1970s?
A figure downloaded from this site.
It represent the history trends of the pollutants related to the photochemical pollution from 1960s to 2000s
We can find that $O_3$, $PAN$, $VOCs$, $...
- 2,479
7
votes
How much worse is the typical subway air, compared to street-level air pollution, in a typical city?
Depends on what type of pollution you are talking about
Moreno et al., 2015 studied this problem in Barcelona, and compared Metro (subway) to trams, buses, and walking in various parts of the city. ...
- 3,376
7
votes
Accepted
How can agricultural ammonia lead to PM2.5 production in the atmosphere?
Acid/Base Chemistry
Gaseous ammonia (NH$_3$) acts as a base when it dissolves in water. The reactions are below.
NH$_3$(g) + H$_2$O(l) $\rightleftharpoons$ NH$_3$(aq)
NH$_3$(aq) + H$_3$O$^+$(aq) $\...
- 2,681
4
votes
But what exactly is "black carbon" in the context of snow-melting particulates reaching Antarctica?
This issue has been extensively studied and identified. A Google search regarding the particle size of black carbon will yield a plethora of information.
Chemically, black carbon (BC) is a component ...
- 41
3
votes
How is the concentration of particulate matter calculated per cubic meter
You mention "volume" which is the crux of the problem: the surface mixing layer changes height throughout the day as solar heating influences the surface. Consider that the same emission ...
- 13.8k
3
votes
Accepted
How to estimate the settling time of atmospheric particulates as a function of aerodynamic size?
I took a class once, and we had an approximate equation for an particle (equation sheet is still up):
$$\frac{d\vec{v}}{dt}=\frac{\rho_{particle}-\rho_{air}}{\rho_{particle}}\vec{g}-\frac{3\rho_{air}...
- 8,809
3
votes
Accepted
What is a Micro-Aethalometer; how do portable Black Carbon (BC) Monitors work?
Following @ Friddy's comment, I started reading Aethlabs AE51 FAQ and was quite surprised!
While a conventional aethalometer use a long tape and move it to the new position after each measurement (...
- 6,904
2
votes
Accepted
How would a particle travel in a hurricane?
You can find diagrams of air flow in hurricanes. If your balloon has neutral buoyancy it will go with the flow. Good luck in the complicated currents in the rainbands and eyewall.
- 2,359
2
votes
But what exactly is "black carbon" in the context of snow-melting particulates reaching Antarctica?
Black carbon, aka "soot", is, in the context of Antarctica, the product of the ocean transport industry that brings tourists and supplies to Antarctica.
Ocean transport is poorly regulated ...
- 2,813
1
vote
Is Luleå's PM10 indicative of poor air quality?
Luleå has a very large steel industry. This coupled with weather conditions, such as temperature inversions would be likely factors for high readings in particulate matter air pollution.
The steel ...
- 24.8k
1
vote
Accepted
How salty can snow/sleet be?
Considering there are evaporation ponds worldwide (San Francisco Bay is full of them, and Morton used to, and may still, have the majority) used for harvesting sea salt, it's doubtful that any salt ...
- 2,187
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