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Member (Idle past 1134 days)
Posts: 167
From: Australia
Joined: 08-15-2016

Message 157 of 191 (816393)
08-03-2017 11:00 PM

2nd Law
The sun adds energy to the earths open system. Since the second law only applies to closed systems, it does not apply to earth. Why is that so hard to understand?

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 Message 159 by Pressie, posted 08-04-2017 4:43 AM Riggamortis has not yet responded
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Member (Idle past 1134 days)
Posts: 167
From: Australia
Joined: 08-15-2016

Message 165 of 191 (816466)
08-04-2017 10:02 PM
Reply to: Message 162 by JonF
08-04-2017 10:05 AM

Re: 2nd Law
The second law applies to all systems. The dS >= Q/T formulation applies only to closed systems.

I admit ignorance of the equations behind the law, is that equation generally the one used to summarise the law? Taken from top google result, hyperphysics.edu;

Second Law of Thermodynamics: In any cyclic process the entropy will either increase or remain the same.

Entropy: a state variable whose change is defined for a reversible process at T where Q is the heat absorbed.

So where is my misunderstanding? I'm guessing 'cyclic' includes in/output systems and the major point of the second law is the conservation of energy regardless of the type of system?

How does a refridgerator relate to any of this? If someone doesn't mind giving me a creationist double-speak-free summation? (Of the creationist argument)

Edited by Riggamortis, : No reason given.

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Member (Idle past 1134 days)
Posts: 167
From: Australia
Joined: 08-15-2016

Message 166 of 191 (816467)
08-04-2017 11:11 PM
Reply to: Message 163 by Taq
08-04-2017 10:28 AM


AndrewPD writes:

So it is statistically unlikely that all the molecules in a gas will go into one corner of a jar because there are to many other possible arrangements. So entropy reflects the unlikelihood of certain formations or order when there is a huge range of other probabilistically available outcomes.

Taq writes:

Take a look at high and low pressure systems in Earth's atmosphere. Those are driven by the Sun.

So no, the gas molecules won't go to the corner of a jar without some outside influence because they 'want' to find equilibrium and stay there at maximum entropy until otherwise disturbed.

The earth is bombarded with energy from the sun which alters the air and ocean temperatures which in turn creates high and low pressure systems. These systems manifest as the weather we observe. It is never able to find a stable, high entropy state due to the energy input from the sun. Climate change is a result of the earth retaining more of the energy it receives from the sun, it follows and is expected that such should produce more extreme weather events. Is this a fair summary of the situation? It leads me to a somewhat related question.

Solar converts the suns rays directly to electricity and therefore not only cuts down on carbon emissions but also somewhat reduces the amount of the suns energy which manifests itself as heat on earth. Since the energy of the wind is ultimately sun powered, in addition to reducing emissions, don't wind turbines reduce the impact of excess energy manifested as weather patterns by removing energy from the wind?

It seems obviously true so the question is, to what extent could it scale? I've not bothered to look into climate change because I'm pro-sustainablility and renewables regardless. Does the climate modelling give numbers in joules of excess energy retained? Could this be compared to global energy usage if we assume we managed 100% wind and solar to see what sort of impact it could have?

In 2014 wiki gives 150,000 TWh generated, anyone got a source for the warming energy and care to do the conversion and comparison?

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