IThe results to last week's Fun Online Poll were as follows:
Why is the earth's surface 30C warmer than it should be, and 60C warmer than the top of Mount Everest?
Greenhouse gases like H2O and CO2 - 20%
Gravity and Boyle's Law warm the lower and cool the upper atmosphere - 67%
Other, please specify - 14%
Which was of course the correct answer. I was told that more specifically I should have said Gay-Lussac's Pressure-Temperature Law:
"The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas's absolute temperature."
(Though having re-read this, they seem to be saying the same thing.)
Atmospheric pressure at ground level is higher than at the highest altitudes, ergo it is warmer than it would be from sunshine alone, and at the top of the atmosphere, it is colder than the average temperature of the whole atmosphere.
Clearly heat can't come from nowhere so what the lower atmosphere gains (in terms of average number of molecules per unit volume with a correspondingly higher total kinetic energy of those molecules per unit volume, colloquially referred to as 'heat') must be balanced out by lower numbers for density, temperature etc in the higher atmosphere .
There is an equilibrium, which depends on how thick the atmosphere is, the air at the bottom can only warm up so far before it rises and cools again; the air can only rise so far before the force of gravity pulling it down overrides its tendency to float up etc.
It's all well and good explaining why the surface temperature is higher than it would be from sunshine alone (and yes, 'greenhouse' gases like H2O, CO2, CH4 contribute a couple of degrees but not a massive amount) if you cannot explain why the upper reaches of the atmosphere* are colder than they would be etc. Any explanation that does not address the latter phenomenon is not coherent or plausible.
* Don't start with the thermosphere, that is high up but hot for very different reasons.
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Going back to a Fun Online Poll of a few weeks ago, 71% thought that Merkel would never realize it was wrong to let a million Muslim refugees into the country.
Interestingly, she sort of did today, although it wasn't really an apology as such, more that she regrets having lost votes over it and wishes she had prepared the ground better before she pressed ahead and did it anyway.
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On the topic of politicians, another politician-avoiding-sugar story popped up again today, I don't know why some people are so obsessed with other people's diets but hey, I try to avoid sugar where poss so he has my sympathy (although I don't make jam, don't really like the stuff).
From The Daily Mail:
* The Labour leader made the comment during a chat on Mumsnet
* Said he shunned biscuits because he was 'anti-sugar on health grounds'
* But mocked as he has a jam-making hobby, which usually involves sugar
Luckily, the internet never forgets. For contrast, there was another politician-avoids-sugar story a while back, which raised no eyebrows whatsoever.
So that's this week's Fun Online Poll (without following that last link first!)
"Which of these politicians avoids sugar?"
Vote here or use the widget in the side bar.
Debate Magazine
