# Tag Info

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The argument is that the air was flowing through the hole at around 700 mph, so the air inside the aircraft had a substantial velocity in the direction of the hole. The air velocity inside the plane would have been less than 700 mph because the flow was converging on the hole, but the speed of the air would still have been hundreds of mph. When the hole was ...

1

Air pressure exists because if we place something in a gas, then the molecules/atoms flying around will keep banging into it, and in this way produce a net constant force per unit area. As explained by @Chris2807 in the neat formula $P=n k_{B} T$, this is proportional to how many particles there are (since this is proportional to the amount of "banging" in ...

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In some sense yes. Let me explain a little. If we were to take a sealed container of gas and put it into free space far away from other bodies so that the gravitational force on the box is negligible would you agree that there would still be some pressure in the container? If we assume we have an ideal gas then the pressure is simply given by $$P=nk_{B}T$$ ...

3

In general, air pressure in the Earth's atmosphere is hydrostatic pressure, caused by the Earth's gravitational field. If there was no gravity then there wouldn't be any centripetal force and all the air molecules would just float away into space. This is why there is no atmosphere on the moon - because it doesn't have enough gravity to sustain one.

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Camera sensitivity is a common topic. In short they mimic the sensitivity of the human eye. Also your statement that we can see violet in pictures of violet objects is not accurate. It refers to violet as a color, not the 'violet wavelengths' of the spectrum. When we see violet objects we do not see 'violet wavelength' light as much as other wavelengths ...

1

Yes: the insolation can be evened out quite a bit. Tidal locking can be an odd half multiple (like 3:2 of Mercury), the orbit eccentric and inclined. A presentation on the SETI Weekly Seminar Series showed simulations of surface temperature maps and was able to get rather uniform results or at least much smoother gradients than previously supposed. Either ...

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I suggest to compare human produced heat with the incident heat of the sun which is around 1 kW/m$^2$. The usual comparison is "the sun delivers more heat in an hour than humans use in a day". While such a comparison may not remain accurate forever, a difference in scale of 7000x suggests that even if humans doubled thei energy consumption every 17 years ...

2

Global energy consumption is $5\times10^{20}\ J/yr$ Assume it is all used to power incandescent lightbulbs, so 95% goes to heating the atmosphere The mass of the atmosphere is $5\times10^{18}\ kg$ The heat capacity of air is $1\times10^{3}\frac{J}{kg\cdot °C}$ Assuming all the heat goes to the atmosphere and stays there, using the definition of heat ...

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Q=mc(t1-t2) You need to calculate C, the specific heat capacity of Earth(as a whole). You need to calculate the specific heat capacity of everything present on, inside earth for that purpose. It might be possible after we advance a bit more further:).

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Starlight, as emitted by a star, comes in a wide range of colours. For instance see the picture below. Now this is a picture, and pictures can often be tricky with their representation of colour, so you'll have to take my word for it that Betelgeuse does look significantly redder to the naked eye than say Vega until you get a chance to go look yourself on ...

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The colour of stars as observed by an observer on Earth varies just like the colour of our own Sun, depending on where in the sky the source is relative to the observer. However, the light of stars is generally too faint to notice this as clearly with the naked eye, because we cannot perceive colour for weak light sources.

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No, Rayleigh scattering models the probability (and angle) of scattering as a function of wavelength and of the particle sizes. All wavelengths travel a long way but the path followed (scatter or nonscatter) varies. Since space is mostly "empty", there's little scattering. Beyond that, your understanding of stars is quite incomplete. THey do in fact have ...

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What causes sunburns is UV radiation, which damages our skin cells. Heat on the other hand is the same as the one felt when near an incandescent light bulb (doesn't cause sunburns). Most of the UV radiation coming from the sun is absorbed by the earth's atmosphere. During sunset and sunrise the radiation emitted by the sun passes through more air until ...

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In general, the sun's light (particularly the UV that causes sunburn) has to pass through a lot more atmosphere (or a greater amount of air mass) in the morning and evening to get to a vertical surface than it does when it is at zenith to a horizontal surface. An example is shown in the generalised image below (all graphs are obviously generalised): The ...

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I would like to expand here on the mechanisms of scattering. Light is scattered by particles in the air which act like dipoles, and oscillate because of the electromagnetic frequency of light. Oscillating dipoles may emit a different frequency. There are two mechanisms of scattering. Rayleigh scattering: This occurs when particle sizes are smaller than ...

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