# Tag Info

42

The atmosphere rotates along with the Earth for the same reason you do. Force isn't needed to make something go. That's a basic law of physics - that a thing that's moving will just keep moving if there's no force on it. Force is needed either to make something change its speed, or to make its motion point in a new direction. A force can do both or just ...

25

The atmosphere of the Earth is mainly composed of nitrogen (N2, 78%) and oxygen (O2, 21%) molecules, which together make up about 99% of its total volume. The remaining 1% contains all sorts of other stuff like argon, water and carbon dioxide, but let's ignore those for now. As you probably know, the oxygen we breathe is produced by plants from water and ...

16

Friction AKA wind resistance. You must have tried to stand in a strong wind or stuck you hand out the window of a traveling vehicle. From that you can feel the force that moving air exerts on objects in its way, and by Newton's law of reaction things in the way exert an equal force tending to move the air up to speed with the ground near it. Even if the ...

15

There are at least two reasons: the air layer adjacent to the Earth surface is dragged with it (being at rest with it). air viscosity -- it could be thought as a friction between different air layers. Upper layers are carried along by underlying layers. If the air were to stop suddenly it would result in ~1500 km/h wind speed. For comparison Hurricane ...

15

Yes, helium can leave the Earth, and yes, we will run out of helium, but because of different reasons. When you buy a helium balloon and its contents get released, this helium goes into the atmosphere. It isn't gone, and it could in principle be purified out of normal air. However, the total amount of helium in the atmosphere is so small it is ...

14

I doubt if anyone has come up with a complete explanation, but some laboratory simulations have created similar patterns. They happen if the central and surrounding areas in a flat, circular disk of fluid have different velocities. Emily Lakdawalla at The Planetary Society covers it at this site. She also explains how other patterns (triangles & ...

13

If you were to surround the atmosphere by an adiabatic envelope and allow it to come to equilibrium, it probably would settle into such a state. However, the atmosphere is not a static place. It is actively mixed due to heating of the ground by the sun, and by cooling of the upper atmosphere by radiation into space. This makes the surface air less dense than ...

8

Temperature generally gets cooler as you go higher in altitude (which is one reason why you have snow on mountain peaks long after it has melted away in the foothills). Hail develops in thunderstorms. A thunderstorm ~BY DEFINITION~ is a storm which has developed through the freezing layer. So think about this: If you see lightning or hear thunder from ...

7

For some atmospheric gases, this is very unlikely, but for some it is possible to a limited extent. Each gas has its own residence time, which is the average time that every substance released into the atmosphere is eventually removed, so that we have a cycle of elements. Also known as biogeochemical cycles, from "Atmospheric Composition, Global ...

6

From the Wikipedia article:(My emphasis) Some people thought that the ozone hole should be above the sources of CFCs. However, CFCs are well mixed globally in the troposphere and the stratosphere. The reason for occurrence of the ozone hole above Antarctica is not because there are more CFCs concentrated but because the low temperatures help form polar ...

6

According to Ahrens R. The bases of cumulus cloud can be estimated quite easily when the surface air temperature and dew point are known. If the air is not too windy, we can assume that entrainment of air will not change the characteristics of a rising thermal. Since the rising air cools at the dry adiabatic rate of about 10°C per 1000 m, and ...

5

In general, yes the updrafts also occur in warm dry air, as a result of heating on the ground which produces hyrdostatic instability in the atmosphere. As the updrafts go higher, they cool adiabatically and may, if they go high enough and if there is enough moisture in the air, cool enough to condense water vapor and form clouds. However there can also be ...

5

Analysis for Jesus's molecule usage: Our breathing rate changes a lot, but on average its about 1 breath every five seconds, or 12 breaths a minute, or 720 breaths an hour, or 17280 breaths a day or 6,307,200 breaths a year, and if we live for 32 years that gives us 201,830,400 breaths in his lifetime. How many atoms? multiply 2.02e8 total ...

4

Logarithmic profile for wind speed regards the bottom part of atmospheric boundary layer (say, about the bottom 100 m, on a boundary layer about 1000 m high). It can be deducted doing some non obvious but reasonable assumptions. A) Vertical flux of horizontal momentum due to turbulence must be uniform in the lowest part of the atmosphere. Let's consider a ...

4

From [The ASCE Standardized Reference Evapotranspiration Equation]1 Given T is temperature in degrees Celsius, and RH is relative humidity: Saturation Vapor Pressure (es) = 0.6108 * exp(17.27 * T / (T + 237.3)) Actual Vapor Pressure (ea) = RH / 100 * es Vapor Pressure Deficit = ea - es Why this is a meaningful measurement: "The strain under which ...

4

Propagation of very energetic photons through medium looks like this. The photon enter the medium, at some point it scatters off an electron or creates an electron-positron pair in a coulomb field, the initial energy distributed between the two daughter particles. Each of these particles then "splits" again, and so on, and as a result an electromagnetic ...

4

I found a reference through Google Books, Very high energy gamma-ray astronomy by Trevor Weekes, which says that the atmosphere is essentially opaque to high-energy gamma rays, equivalent to a meter-thick wall of lead. We are able to do gamma-ray astronomy with ground-based telescopes by detecting the decay products of the gamma rays' interactions with ...

4

The greenhouse effect is well-established science, and experiments that demonstrate the effect on a lab scale are common to the point that they are often presented in science fairs. When I say "greenhouse effect" in this context, I'm referring to the radiative trapping of heat by absorption of outgoing radiation by gases. As has been pointed out on Physics ...

4

Cumulous clouds form when the atmosphere gets unstable. For incompressible liquids, "unstable" means a high density liquid "water" is balancing precariously on a low density liquid "oil" (ignore surface tension). If a little bit of the lower density liquid rises, it will act like a "bubble", and will be pushed upward. The updraft will cause a positive ...

4

Mars does have an atmosphere. Iron oxide dust in the atmosphere contributes to its redness, though without this dust it would still be colored. As a side note, our Moon has very little atmosphere. If you paint the Moon's surface pink, it'll reflect the sun's light and look pink, even without an atmosphere.

4

It might affect climate, but not on the time scale of a month, and does not significantly affect the weather. The fact that the moon exists may significantly stabilise the inclination of the Earth relative to the Sun. This, in turn, affects climate in the long run. The debate is ongoing. For example, see long term axial tilt (Wikipedia): The Moon has ...

3

Ultimately, the power source can be traced back to the sun. This supplies the heat energy to cause the atmospheric movements which give rise to the charge separation in Jack's answer. I don't think it's feasible to do it artificially the same way (charge separation on water droplets/ice crystals). You would need an environmental chamber of size of the ...

3

You need to distinguish between the greenhouse effect, which is well established, and anthropogenic global warming, which is rather more controversial. The greenhouse effect is due to gases like water vapour and carbon dioxide that allow visible light to pass through them but scatter infrared light. This causes the planet to warm up just like a greenhouse ...

3

I would not claim to understand what precisely is going on here, but other things remnaining constant, mathematically you have: $$\lim_{L \rightarrow 0} \quad p_0 \cdot \left(1 - \frac{L \cdot h}{T_0} \right)^\frac{g \cdot M}{R \cdot L} = p_0 \cdot \exp \left( - \frac{ h \cdot g \cdot M}{T_0 \cdot R} \right)$$

3

Mirages are a visible effect of the inhomogeneous, temperature-dependent refractive index of air. They're visible because of the relatively large heat gradient close to the earth's surface, and the excellent reference line provided by a uniform, flat horizon. I think those conditions would be difficult to replicate in-flight - perhaps you could have a drone ...

3

Air of different temperature and pressure has different refractive index - but the difference is very small. If you think of putting a piece of glass into water and trying to see it. The difference between glass (1.5) and water (1.33) is pretty large, air at different temperatures has refractive index differences of parts-per-million Astronomers at least ...

3

Climate modelling is a giant science of its own, and the proportion of CFD/statistics depends on the particular model. In general, what models do is first a simple (often uncompressable) large-scale CFD to advect the scalar fields and then apply a bunch of subrutines simulating small scale and more complex processes, like radiation transfers, heat transfers, ...

3

There's always a reason although for different weather fronts, the discussion has to be different. Different densities have to have a reason - different pressure and/or humidity etc. If there is a different pressure, there is a mechanical force the preserves the pressure difference: think about the cyclones that have a lower pressure in the center. The ...

3

I wasn't going to answer, since this is a duplicate, but I saw these clouds on the way to work and since they are relevant for the question I thought I'd post them. Look closely at the clouds and you'll see their bottoms are flat. That's because they are being shaped by air currents (thermals) rising from below the clouds. The average density of a cloud ...

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