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Earth's Energy System

  1. Dec 4, 2006 #1
    Those who talk about global warming take a very superficial view of earth’s energy system. Even many who call themselves scientists seem to think earth is a simple system of solar radiation in, heating of earth's matter and radiation out. They believe that earth must radiate as much energy out as it absorbs or it will become hotter. They ignore the role of the biosphere and the complex energy role of water. Earth would be uninhabitable if it didn't convert much of the solar radiation it receives into other forms of energy besides heat.

    Much of the energy on earth exists as potential energy rather than just the specific form of kinetic energy known as heat energy. The standard definition of “heat energy” is the motion of atoms/molecules. Gas molecules actually move around more as they become “hotter”. Molecules that are part of a solid cannot move independently so they vibrate along with the other molecules that are part of the solid. Kinetic energy includes wind and objects moving through the air or along the ground. This motion is not a form of heat energy, but friction caused by moving through the air, particularly for falling objects, may raise the temperature of the object.

    Earth’s climate cannot be understood without examining its complex energy system.

    Solar radiation provides most of the energy for earth. Radiation hitting solid and liquid portions of earth is converted into heat energy. Some radiation also heats the atmosphere directly. Plants use solar radiation to store energy in the form of chemical bonds of complex carbon molecules. This energy is a from of potential energy. Cold blooded animals, and even some warm blooded animals, use solar radiation for heat. Humans use radiation to produce vitamin D and changes in skin pigment. A significant amount of solar radiation is reflected back into space.


    Water plays a major role in earth’s energy system. In solid form as ice and snow it reflects most radiation striking it back into space. Dirt or soot in the snow may convert radiation into heat energy. Liquid water has a more complicated role. In the liquid state, water is transparent to solar radiation but also reflects some radiation into space depending on the angle at which the radiation strikes it. Plants in water like plants on land store radiation in carbon molecules. Fish are heated by solar radiation, or the heat in the water. They use the heat energy for growth and to move around. If the ocean fish populations decline, this heat energy will not be converted to increasing the mass of the fish or powering their movements. The oceans will warm as a result.

    Traditional physics recognizes three basic forms of heat transfer: conduction, radiation and convection. Physicists ignore a fourth form of heat energy transfer, evaporation of water, because it does not directly change temperature. Those who talk about global warming concentrate on the radiation and ignore the fact that earth isn’t a good radiator. Most of the earth is covered by water which isn’t a good radiator because it is either reflective or transparent to radiation. Substances which are transparent or reflective are poor radiators.


    The complete essary is at:


    http://www.writing.com/main/view_item/item_id/1181679
     
  2. jcsd
  3. Dec 4, 2006 #2
    Evaporation is a cooling process, all good scientists recognize this. Say you've got a pool of water that is heated by solar radiation. The molecules with the most kinetic energy will escape the pool leaving behind the slower, cooler molecules. As the faster molecules are removed the average temperature of the pool will drop unless the solar radiation is overcompensating for the lost fast molecules.

    Also you haven't mentioned the earth's geothermal heat. regardless all the climate modellers I know will account for this in their models.
     
  4. Dec 4, 2006 #3
    Nice try, RML, Not bad. A remark about this part.

    billiards, Evaporation is indeed a cooling process but the heat is returned during condensation. So baiscally the water cycle is also a heat transfer process, from the earth surface to the atmosphere. It's called "latent heat".
     
  5. Dec 4, 2006 #4
    andre i knew that. but thanks anyway.

    incidentally geothermal heat can be transferred to the atmosphere by the advection of groundwater also
     
  6. Dec 4, 2006 #5
    I've heard that Venus is an anomaly in our solar system because it is radiating more heat than it absorbs

    http://adsabs.harvard.edu/abs/1994JGR....99.2019A

    There are also signs that Saturn is doing the same thing.
    Is Earth still pretty hot in that regard?
     
  7. Dec 5, 2006 #6
    Nannoh, I'm afraid that your link to Venus doesn't work, probably because it's abbreviated with the dots "1994JGR....99". I would appreciate it if you would try and correct it.

    Yes, there was quite some commotion about the apparant excess radiation of Venus some decades ago but it was shovelled under the carpet, probably instrument errors, since it cannot be explained. So I'm very anxiously awaiting the results of the Venus Express, which is currently orbitting the planet.

    A long time ago I had a thread in PF explaining that excess heat, and that idea would also explain it for the gas giants. However, although the idea is following the scientific method (observation - physical feasible explanation - prediction (like confrimed excess heat) etc) it's not allowed to discuss it here, since it's against the mainstream.

    Don't worry about Earth. It's not due for Venus' fate for the next billions of years or so, thanks to our moon.
     
    Last edited: Dec 5, 2006
  8. Dec 5, 2006 #7
    Thank you for the show of interest.

    Not due? I have been led to understand that Venus us much much younger than Earth.

    Sorry for the malfunctory link.

    The address actually has the dots in it. Here it is again with the abstract from the article.

    http://adsabs.harvard.edu/abs/1994JGR....99.2019A

     
  9. Dec 5, 2006 #8
    Thanks Nannoh, but link still doesn't work.

    Anyway, there are a few dozen hypetheses about the current condition of Venus, apart from it's excess radiation (if confirmed) there is also its retrogade rotation (243 days), its heat (~470C), it's volcanism, its atmosphere (~92 bar, 95% CO2), it's young surface (~700Ma), its lack of magnetism, lack of plate tectenics, gravitation highly corrolating with terrain features, peculiar features like coronaea, etc, etc.

    None but one hypothesis addresses all features simulatenously.

    Have a look here
     
  10. Dec 5, 2006 #9
    Thank you for trying. As you can see the abstract is there for the reading.

    I followed your link and 3 out of 5 of the links are dead and one is moved by NASA. something fishy about Venus!!!

    I kept on reading and you mentioned this fact

    And so is the earth's crust another gyroscope. This is probably what causes the illusion of magnetic pole movements. Displacement of the crust in relation to the mantel and to the core. As the crust rides the mantle the magnetic poles do not change however to us it appears that the magnetic poles are changing when actually it is the crust (where we live) that is moving over the poles. This would account for regional climate changes. As a northern portion of the crust is dragged into the magnetic pole its climate cools. As the corresponding portion of the crust is dumped toward the equator, it is warming. Then you see the opposite happen at the southern magnetic pole. Its entirely possible to track these changes by recording temperature stats around the poles and doing careful comparisons.

    On another completely unrelated topic, how did NASA arrive at 700 or 500 million years old activities on Venus? How have they actually dated the planet? Simply by observing the results of geomorphic processes or by samples?
     
  11. Dec 6, 2006 #10
    Your theory about the magnetic poles not moving cannot be fully correct. Historical records (I believe since the Victorians) show that the "declination" - or the position of the magnetic pole relative to the geographical pole moves relatively quickly, and has no consistent orientation (it kinda circles around the north pole). As for your climate records I believe you have grossly over simplified it, the fact is people are arguing about whether there was an ice age 40 million years ago (not really that far back at geologic timescales), our climate records get ever cruder the further back we go - that is - we see large scale global patterns but we miss the finer details.

    As for dating volcanoes on Venus, I presume it has been done by studying impact craters. The age is then calculated by statistical mean, as in - they know roughly how many impacts there were in the time period and if the volcanic deposits have been affected by impacts this much then they calculate how long they've been around. I'm not a planetary scientist but I believe that is how they do it - they use bodies that do not refresh their surface to wotkout the impact rate and find it decreases exponentially.

    According to the most widely accepted model for solar system formation, all planets condensed for a cloud of dust about the same time ~4.5 billion years ago.
     
  12. Dec 6, 2006 #11
    Thank you for pointing out my over simplifications. The wandering of the magnetic pole could also be attributed to what Andre points to as a gyroscopic motion of the earths core. This all makes me want to study geology and planetary science a lot more. Thanks again!
     
  13. Dec 7, 2006 #12
    Nannoh,

    The last idea about the earth magnetic field is that it is generated by convection flows in the fluid other core in multiple thermal convection cell. Those cells are supposed to counter rotate, generation opposing magnetic fields. The Earth magnetic field is the resultant of the sum of all those positive and negative field. Slight changes in the convection cells can have large influence on the resultant magnetic field, even reversing it, which has happened every few 100,000 years.

    Billiards, dating Venus surface indeed is the result of studying the impact craters, about 900 in total, no more. Additional to those you mention, the crater density, there is also the state of the craters, craters filled in with lava, etc and erosion is also used to estimate chronologies. The dense atmosphere appears to be strong enough to move particles, eroding the craters.
     
  14. Dec 8, 2006 #13
    Since the earth's magnetic field could be construed to be part of the earth's energy system we seem to on topic still! What is causing any slight changes in the convection cells of the mantel? Do they rotate with the planet or are they back-eddies or something else? Do these changes effect the lithosphere and if so is it a wholeistic effect or regional? Thanks.
     
  15. Dec 8, 2006 #14
    I don't think anyone could give you an honest answer to those questions because we still don't understand what's really going on down there. Presumably convection occurs in places where there is a lot of heat, and radiation and conduction are not effective heat transfering mechanisms.

    We can say for sure that any system would rotate with the planet although it would also be affected by the planets rotation, especially if the current was perpendicular to the spin axis - that might cause what's known as coriolis deflection. Convection currents would affect the lithosphere, it is possible that they drive plate tectonics and if plume theory is to be believed (which I think it can be!) it also explains "hot" spot volcanism, e.g. Hawaii. Although not many people know that the Hawaiian volcanic chain does not perfectly match the tectonic movement but there is also a "wind" that has blown the convection current slightly changing the absolute position of the "hot" spot.

    Earth's magnetism is probably due to electrical eddies in the liquid outer core.
     
  16. Dec 8, 2006 #15
    Planetary physiology is fairly complicated! I'd say you've probably given me the best answers I'll get with regard to my questions.

    Here's one more! Is the magnetic field possibly caused by the friction or static electricity going on between various densities and mineral compositions in the liquid outer core? Is this source of energy the same source that Nicholi Tesla was attempting to tap into with his coils and other inventions?

    I saw a demonstration of Tesla's Earthquake machine. Its powered by small electomagnets interchanging polarities or something. There was one that had been engineered and built that was only about a foot long. After attaching it to a bridge span of about half a mile for 2 hours this little magnetic motor had begun to vibrate every inch of the bridge's metal structure.
     
  17. Jan 29, 2007 #16
    Do you have a weblink or source for that demonstration??
     
  18. Jan 29, 2007 #17
    NANNOH said:


    "I've heard that Venus is an anomaly in our solar system because it is radiating more heat than it absorbs"

    The excess heat of some planets has been hypothesised by J Marvin Herndon
    to result from nuclear fission at the planet cores.But what if the excess comes from chemical reactions or phase changes like crystallisation.
     
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