Earth as a Control Volume

[Jabberwocky]

Hello all, I wasn't sure where to put this, but I think history has the most bearing.

Taking the Earth as a control volume, say a sphere 2 miles off of sea level - are we losing or gaining?

Input I could see as solar energy, meteor(ites), comets, dust etc.

Output I see as satellites, spaceships, and all hydrogen/helium we "create" from other compounds.

What does everybody think, will we run out of "stuff"? (not on an entropic basis, just in terms of throwing things off-planet)

 

[25362]

The mass of Earth is estimated at 6[×]10²⁴ kg.

It is estimated that 1,000,000 kg of micrometeorites fall on Earth every day, and they appear to be falling at the same rate for, say, some 5 billions years; the total mass addition would be:

(10⁶ Kg/day)(365 days/year)(5[×]10⁹ years) = 2 [×] 10¹⁸ kg​

ie, less than one millionth of Earth's mass, it is logical to assume the micrometeorites' contribution to Earth's mass is, in fact, insignificant.

 

[Jabberwocky]

Ok, that's good numerical stuff - are we losing more than that through chemical processing and space travel?

 

[IRstuff]

Does it matter?

Let's say it's 10^9 kg loss per day (which it's not). Over the lifetime of yourself, your children and your grandchildren, say 150 yrs, that amounts to less than 1 billionth of 1% of the Earth's mass.

TTFN

 

[TheTick]

Do you really consider released helium and hydrogen as lost mass? Are they leaving the atmosphere or just floating to the top layers? Aren't the gases are still held by gravity and also contributing to the total gravitational field?

 

[IRstuff]

Supposedly, helium and hydrogen, if released, will go their merry way into the Milky Way. Prior to that, they would be tightly bonded to physical things and contribute. Once they get above us, they don't contribute to gravity, at least, not for us on the ground.

TTFN

 

[Tobalcane]

Well according to the law of conservation of mass, we are not loosing anything on earth, but since we are bombarded by meteorites I say we are gaining…

Just my 2.5 cents


Go Mechanical Engineering
Tobalcane

 

[rb1957]

isn't some of the atmosphere being leeched away into space ?

actually this thread is a good initiation point for global warming. the key question (IMHO) is how much is the global weather being affected by human activities ? if we're causing the changes (which i personally doubt) then we should be able to affect change. if the system is so large that the human contribution is tiny (trivial) then we're going where the system is taking us (like the flea on the dog) even if we don't like it.

thoughts ?

 

[IRstuff]

That presumption is belied by reality.

Have you noticed that London no longer has "killer" fog? It turns out that London started to not have heavy fog, once people stopped using wood for heating and cooking.

The earth's atmosphere is a highly non-linear, positive-feedback system. Small perturbances get rapidly magnified. The growth of a hurricane would be impossible in a linear system. Yet, we can see both non-linearity and positive feedback in a hurricane system.

Likewise, while our contributions might appear small, they alter the balance and the disturbance gets amplified. Ozone destruction has at least slowed, once we stopped using the worst of the chlorocarbons. Once we reduce or at least stop the growth of our contributions of greenhouse gases, there's some hope that global warming will at least slow down.

Benoit's origination of chaos theory arose from the observation that a less than 1 ppm change in atmospheric variables would radically alter climate outcomes, over a very short time scale. Over larger time scales, even a less than 1 ppb change would affect the net outcome.

TTFN

 

[rmw]

Read the answer to the question from Rory. Makes for some interesting introspection, huh?

rmw

http://thestormtrack.com/archives/2005/10/are_hurricanes.html

 

[zeitghost]

Wood burning?

Don't think so.

The fogs were caused by burning coal in open grates.

Cured by changing to burning smokeless fuel briquettes.

Which moved the pollution from London to the mining areas where the smokeless fuel was produced.

In stinking plants like the Phurnacite one in Aberdare...