# Tag Info

1

Simple black body radiation theory (adapted from http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html): The earth receives a certain amount of heat per unit area from the sun - this amount is about 1370 W/m$^2$ for parts of the earth facing the sun when there is no atmosphere. But the earth presents a "disk" with area $\pi R^2$ to the sun, when ...

4

It is actually very easy to consider this. We don't need any models. we are blessed with a sizable rock at exactly 1 AU from the Sun, a rock with no trace of any atmosphere at all: Moon (Source: Wikimedia Commons) Temperatures on the moon vary from 70K to 390K. Average temperatures, depending on location, vary from 130K at the poles to 220K at the ...

0

This is an extremely complex question, because the behavior of the atmosphere is extremely complex. There are a couple of “effects” of the atmosphere I can think from the top of my head: the greenhouse effect you have mentioned, which heats the planet the reduced thermal amplitude, which also, on average, heats the planet The last point comes from the ...

-3

All things being equal, I would tend to believe that water or vapor molecules are larger, tougher, and thus encountered more frequently thus slowing the bullet down.

0

I would like to add that on Jupiter bands are more evidente because the rotational speed of the planet is much bigger. Jupiter has a rotation period of about 11 hours and a radius 12 times that of earth.

1

The most common colour for the sky on Earth is a white sky. Clouds cover around 70% of the Earth, and the nature by which they are scattering shortwave radiation makes them appear white or grey. This is because photons coming from the Sun are likely to be scattered multiple times, and because the dependence on wavelength is not strongly increasing or ...

2

This is an extremely hard question to answer definitely; its answer is heavily dependent on three things (1) the makeup of the atmosphere in question (2) the density of the atmosphere in question and (3) the surface temperature, and therefore the spectrum of output light, of the star in question. If the atmopsphere's gasses are themselves are coloured (e.g. ...

0

Hmm... Mars has a red sky. But that's cause of the iron content in the soil absorbs other parts of the visible spectrum and reflects back the red part, so the sky looks reddish. I do not think a blackish sky was too far-fetched cause carbon tends to be black, smoke is blackish grey. Perceived color depends on different elements absorbing different portions ...

17

Average human body volume = 0.0664 $m^3$ (seems low to me, but that's according to Wolfram Alpha: http://www.wolframalpha.com/input/?i=volume+human+body). Density of air depends on temperature and pressure, but is about 1.2 or 1.3 $kg/m^3$. That means we displace, on average, about 80 g of air, giving us a buoyancy of about 0.8 N (about 1/6 lb). The ...

7

You will displace air equal to your volume. If your volume is $v$,you will displace air of volume $v$, If the density of air is $d$, then the mass of the air displaced will be equal to the product of volume and density. and thus force on you according to Archimedes ' principle =$vdg$, 'g' is the acceleration due to gravity. Archimedes' principle indicates ...

1

Not much. By Archimedes principle the buoyant force is equal to the weight of the volume of fluid displaced, which would be the volume of your body. And the fluid is air. So you would only be slightly heavier than you are now if there was a vacuum at the earth's surface.

3

There's all kinds of awesome and complicated stuff going on in that image... so let's look at a much simpler one to see what you mean (source): At the equator, the predominant wind direction is easterly, or opposite the direction of Earth rotation. Away from the equator, north of 30 degrees, the winds are primarily westerly, with the direction of ...

28

The short answer is -- there are bands! They behave very similar to the bands on Jupiter, but are not as pronounced. And we don't have a really unappealing colored atmosphere to show us what the bands look like. Here is an example of what they look like (source): There are two bands along each side of the equator. Another set of bands starts 30 degrees ...

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