Global warming

Thomas je 22. okt 2010 ob 13:46 izjavil:

Na zunanjo stran Dysonove sfere daj popolni izolator, dobro pustiš malo odprtine, da ma toplota kam iti in se lahko ravnovesje vzpostavi.

V tem primeru pa se poveča temperatura Dysonove sfere YES/NO?

Če je zunaj črna, ta Dysonova sfera in gor nalimaš (OD ZUNAJ!) 1 km steklene volne, bo zunanja površina te seklene volne prišla na 0. Not, pa metrov globoko v volni, je pa lahko 1000 stopinj. Pleh še globje, celo izpari!

Tako je Dysonova sfera se segreje lahko enormno, v kolikor imaš neskončno dobro izolacijo, lahko vzamemo kar 100% odbojna zrcala, namesto kilometrov steklene volne, še bolj nazoren prikaz, ker potem konvekcije nimaš, ki zmanjša to temperaturo. Zaradi tankosti tudi ne ločimo zunanje in notranje strani sfere, je zadosti tanka, da je enaka, kot je WarpedOne izpostavil.

Najbolje da vzamemo samo pol sfere, ker potem sfera na strani kjer ima atmosfero oddaja v praznino toploto in ne sama sebi.

Tako pridem lepo do učinka tople grede na polovici Dysonove sfere, ki ga povzroča atmosfera, pod pogojem, da zunanja stran sfere ne more oddati energije. No lahko imamo tudi mrzlo gredo, če je atmosfera drugačne sestave.

Pa jo imamo še na sferi, da ne bomo ekskluziv za planete delal.

Iz napačne predpostavke lahko izpelješ karkoli.
Nespremenjena okolica (zunanjost) je predpostavka. Spreminjaš notranjost, kjer imaš pa nespremnjen vir - sonce.
Sej pravm - površno branje.

WarpedGone je 22. okt 2010 ob 15:44 izjavil:

Če so jajca gladka ne pomeni da mačke niso kosmate.

No, nekatere dejansko niso kosmate.

CO2 ima v Dysonovi sferi bilanco 0. Kar zadrži, odbije v drug konec sfere, magari via Sonce. Na planetu pa vsaj nekaj fotonov preusmeri v črno nebo in ti nikoli ne zadanejo tal. Tako hladi.

Še dobro da imamo spektrograme.

Pyro ... no offence, ampak še hujše napake delaš kot JJ. No ja, enake.

Prove me wrong.

Ti enačiš in povprečiš stvari tam kjer se nebi smele in se na drugi strani zapikuješ v irelevantne faktorje.

In ti se ne potrudiš razložiti in pokazati napake.

Eh.

Za primer Dysonove sfere je izolacija znotraj bučke pravilna in se strinjam z njo. Njena temperatura je enaka, neglede na medij znotraj (če je bučka netransparentna)

Razporeditev temperature ni enakomerna, ko se oddaljujemo od vira sevanja, lahko bodo toplejša in hladnejša območja, glede na posamezne meteriale.

CO2 ima v Dysonovi sferi bilanco 0. Kar zadrži fotonov visoko nad tlemi, jih odbije v drug konec sfere, magari via Sonce. Na planetu pa vsaj nekaj fotonov preusmeri v črno nebo in ti nikoli ne zadanejo tal. Tako hladi.

Se pravi si zopet vse povedal. Ta primer torej ni analogen Co2 na zemlji in topli gredi.

Protislovja pišeš, ko se rešuješ iz zagate. Očitno si sedaj napisal, da je na zemlji pri CO2 razlika kot pri sferi, preberi se. Kaj čmo tle, po potrebi boš obračal ploščo kot si jo že večkrat, enkrat bo analogno drugič ne.

Med sonce in nas lahko damo lečo ali pa ogledala ki bi ujela drugače mimobežno svetlobo in s tem povečamo absorpcijo (Več W na m2) in s tem tudi temperaturo površja (Večanje notranje energije), dokler se emisivnost spet ne izenači vnosom energije.

Enako storimo z ogromnim ogledalom za našim planetom, s čimer bi ohranjali izsevano energijo.

Ja. S sicer mimo bežečo svetlobo, bi se lahko nekoliko ogreli. To drži. Vendar nam je atmosferski CO2, tiste ne lovi. Še nekaj nam namenjene - tako kot vsi plini nad nami - odžene.

Še vedno si globoko v zablodi, sožalje.

To je popolnoma res, atmosfera pobere kar veliko energije, sploh skoraj vso UV, nekaj jo tudi odbije.


Samo taka pobrana energija se spet izseva, tokrat v obliki IR, v obe smeri. Nimam pojma zakaj se graf konča pri 2700nm, ko sploh ne pokrije IR-C spektra ki bi ga moralo biti kar precej.

No pol pa povej zakaj imamo na ceveh izolatorje... če itak bo v eni uri ko se segreje enako topel neglede kakšna snov je to.

Dobro vprašanje. Najprej poskusi najti odgovor sam.

Kaj nas pol greje vidna svetloba iz sonca in ne njegov IR ?

Pretežno, ja.

The greenhouse effect is extremely vital to the Earth. Without it, the Earth would be 30 degrees cooler than it actually is. Its important to understand why the natural greenhouse effect raises temperatures slight, yet doesn't causes run away heating on earth.

First I'll begin by describing the Earth's energy budget.

The Earth absorbs 48% of incoming solar energy. So, processes on the ground must get rid of the 48 percent of incoming solar energy that the ocean and land surfaces absorb. (If they didn't temperatures would rise infinitely.) Energy leaves the surface through three processes: evaporation, convection, and emission of thermal infrared energy (which you described).

About 25 percent of incoming solar energy leaves the surface through evaporation. An additional 5% of heat leaves the surface through convection. Finally, a net of about 17% of heat leaves the surface as thermal inferred energy (heat).

Next I'll explain a natural greenhouse effect:
Water vapor, carbon dioxide, methane, and other trace gases are opaque to many wavelengths of thermal infrared energy. Remember that the surface radiates the net equivalent of 17 percent of incoming solar energy as thermal infrared. However, the amount that directly escapes to space is only about 12 percent of incoming solar energy. The remaining fraction—a net 5-6 percent of incoming solar energy—is transferred to the atmosphere when greenhouse gas molecules absorb thermal infrared energy radiated by the surface.

When greenhouse gas molecules absorb thermal infrared energy, their temperature rises. Greenhouse gases then radiate an increased amount of thermal infrared energy in all directions.Because greenhouse gas molecules radiate heat in all directions, some of it spreads downward and ultimately comes back into contact with the Earth’s surface, where it is absorbed. This heating is known as the natural greenhouse effect.

The natural greenhouse effect raises the Earth’s surface temperature to about 15 degrees Celsius on average—more than 30 degrees warmer than it would be if it didn’t have an atmosphere. The amount of heat radiated from the atmosphere to the surface (sometimes called “back radiation”) is equivalent to 100 percent of the incoming solar energy. Now the Earth's surface is absorbing 1an equivalent of 148% of incoming solar energy. However, processes on the ground are only getting rid of 48%. Thus, temperatures have almost doubled.

However, temperatures will not continue to rise. As you stated, the amount of energy a surface radiates always increases faster than its temperature rises—outgoing energy increases with the fourth power of temperature. So, the surface will releases an increasing amount of heat—equivalent to about 117 percent of incoming solar energy. Now the Earth is absorbing an equivalent of 148% of solar energy. Yet, it is releasing 148% of solar energy. So, temperatures will not rise anymore.

Now I'll describe an extreme greenhouse effect.

More greenhouse gasses let fewer thermal inferred energy (emitted by the Earth) escape to space. So, more than an equivalent of 100% of solar radiation is returning to Earth as back radiation. Thus, temperatures will continue to rise, until the amount of greenhouse gases in the atmosphere returns to normal.

Sej to je blo za Pyrota... ti vem da si nehal po prvem stavku.

JJ je od nekod skopiral:

However, temperatures will not continue to rise. As you stated, the amount of energy a surface radiates always increases faster than its temperature rises--outgoing energy increases with the fourth power of temperature. So, the surface will releases an increasing amount of heat--equivalent to about 117 percent of incoming solar energy. Now the Earth is absorbing an equivalent of 148% of solar energy. Yet, it is releasing 148% of solar energy. So, temperatures will not rise anymore.

Pošlji ga nazaj v srednjo šolo.

The greenhouse effect is extremely vital to the Earth. Without it, the Earth would be 30 degrees cooler than it actually is.

JJ, a ti resno zagovarjaš tezo, da bi površina zemlje (overall) bila bolj hladna, če ne bi bilo atmosfere?

o+ nevone

Ja nevone bi bila, brez celotne atmosfere bi bilo največ okoli 0 stopinj.

Drugače pa...

http://www2.arnes.si/~kvidma2/Ucila_GJV...

Atmosfera akumulira toploto podobno kot oceani.

o+ nevone

This page presents a simple physical model of the greenhouse effect that demonstrates how the blanketing effect of greenhouse gases in the atmosphere can elevate the surface temperature of a planet. The model is an instructional "toy model," meaning it strips the process down to its essential elements so that the basic ideas are easy to convey. Models that are used to make predictions by climate experts are substantially more sophisticated, but at root the physics are similar to what is described below.

Ja lej tkole je. Ti pa rečem, da ne boš našla modelov, ki bi izmerili, da nas atmosfera hladi.

Nobene kršitve energijskega zakona, če te bo železna cev z vročo vodo spekla, plastična pa ne. Tako da, naj si vsak razčisti.

Ja lej tkole je. Ti pa rečem, da ne boš našla modelov, ki bi izmerili, da nas atmosfera hladi.

Sej nas dodatno ne hladi, prav tako kot nas dodatno ne greje. Podnevi je hladneje kot bi bilo sicer, ponoči je pa topleje, kot bi bilo sicer.

o+ nevone

Drugič pa to, da je plastika slabši prevodnik in ohlajena površina plastike ni takoj segreta iz notranjosti, kakor je to pri kovini.

Ne samo da ni takoj, sploh ni. Ne boš se spekel nikoli.