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17

If you are smelling something, you are inhaling gases, particles, or a combination of the two. They don't normally build up in the atmosphere because of three reasons: transport/dilution (which you mentioned), chemistry, and deposition. Yes there is plenty of fresh air out there but as you say, over billions of years there would be a lot of accumulation ...


11

Saying that warm air "holds" more moisture is technically incorrect, but is a common colloquialism. Let's break it down to the technicalities. Let's consider a glass of water with a vacuum (no air) above it. What will happen? The molecules that are at the top most layer of the water will evaporate. At what rate will the water evaporate? Better yet, what is ...


10

[Major edits below] In short the answer is NO. Before we get into volume changes, I have to say that volume is a tricky measure to apply to the atmosphere as a whole, because there is no clear limit between the atmosphere and outer space. Also, the thickness of the atmosphere is quite insensitive to changes in atmospheric mass. For example, the atmosphere ...


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

Air is a fluid, as such it tends to mix and concentrations, of anything, tend to disperse into the wider volume. Erik's cup of tea metaphor is pretty accurate, currents of air will pull apart your exemplar 1m3 and disperse the pollutants therein, the heavier particulate, which is mainly soot, water droplets from combustion, and unburned fuel, will full to ...


7

So, naively, one would expect the heavier gasses to pool in the lower atmosphere and the light ones at the top. That's overly naive. That same naive expectation would lead one to think that uranium should be concentrated in the Earth's core, or that a mix of water and ethanol should be differentiated with water on the bottom and ethanol on top. Uranium is ...


6

But despite of that, there is no reports of miners dying because on the top of the cavity the air was only nitrogen or oxygen at the bottom. Yes and no, miners die from other causes, like lack of oxygen, sulphur poisoning, etc. But for example you can already get a case of sulphur poisoning near Fumaroles in volcanic regions, simply because the air that has ...


5

Like many of my answers on this Stack Exchange, the answer is yes and no. Part of it depends on the pollutant itself. Let's call the mass by it's technical term, a parcel. There are a couple things that can change the pollution level of the parcel, other than the source (a car in your example): Chemical reactions between the pollutant, the parcel, light, ...


5

The water molecule is just another molecule in the atmosphere - except that it's triatomic, whereas 99.97% of the dry atmosphere is monatomic (Argon) and diatomic (Oxygen and Nitrogen). It's also slightly electrically polarized, and because of this it has a low energy state when in the presence of similar molecules (liquid or solid form), and at a higher ...


5

What is the deep physics or chemistry reason this happens? In one word, entropy. In a thousand words (i.e., a picture), Source: Wikipedia article on Phase Diagram The above is a phase diagram of water. The curve of interest is that between vapor (tan area) and solid or liquid (blue and green areas). For a given temperature (a vertical line in the diagram)...


4

You are correct that air generally moves along the surface from high pressure towards low pressure (not directly, but deflected due to the coriolis effect). However, this does not imply that it is moving from a colder area to a warmer area. And, there is nothing contradictory in a cool air mass moving horizontally to displace a warm air mass. Extratropical ...


4

Let me answer this question indirectly. When a pressure cooker partially filled with liquid water is heated up, there will be more water vapour molecules in the air inside pressure cooker but volume of pressure cooker still remains same. Only thing that changes inside the pressure cooker is pressure and temperature of air. Volume of gas is determined by ...


1

From Wikipedia: In automobiles, a start-stop system or stop-start system automatically shuts down and restarts the internal combustion engine to reduce the amount of time the engine spends idling, thereby reducing fuel consumption and emissions. This is most advantageous for vehicles which spend significant amounts of time waiting at traffic lights or ...


1

Generally idling will cause pollution in specific isolated areas and start stop technology could irradicate that pollution. Here I will concentrate not on the global impact of the pollutants but at the location where the pollution is released. The differing scenarios are important to how much of an effect start-stop / idling will have on air quality. The ...


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