frank_davis (frank_davis) wrote,

Hope It's Cloudy Tomorrow

Gorgeous sunny day. I sat down by the river today, with a pint of chilled lager and a cigar. The river was as pretty as a picture. It's the fourth day in succession that I've done this. That must be a record. Since the smoking ban, summers have been dismal. But that looks set to change this year, maybe. It might be a scorcher.

But if that happens, then for sure the global warmists will start sounding the alarm again. Because they haven't gone away. Public confidence in climate science may have been collapsing over the past 6 months since the Climategate scandal broke in late November last year, but the established scientific consensus seems to remain solid that global warming is happening, and that everybody must use watery dimbulbs and pay carbon taxes on just about everything. So there's bound to be a new drive to set out to restore public confidence. It'll probably be headed up by a few celebrities. They probably have a Global Warming Awareness Week, during which a long train of boffins will come on air telling everyone just how bad/hot it's going to get, interspersed with dancing girls in skimpy Global Warming Awareness bikinis.

I don't know why they don't take a leaf out of the tobacco playbook and just declare that 75% of people are more than happy with Global Warming, and find that life has been so much better since Global Warming, and theyre all dying to install dimbulbs and dispose of their cars and stop heating their houses in winter. Why don't they just fabricate public opinion? They do it with smoking, after all.

A week or so back I put together a simple computer simulation model of a square metre of surface earth on the equator of a spinning atmosphereless planet . I was wondering whether it made much difference whether the planet spun fast or slow. All it showed was that on a slow-spinning planet the surface temperature got a lot hotter during the day, and a lot colder at night, than on a fast-spinng planet. The average temperature remained the same. No surprise there.

Now I've added a simple homogeneous atmosphere on top of the square metre of earth. I've found out that there's 10,000 kg of atmosphere above every square metre of the earth's surface. And I've found that 19% of sunlight is absorbed by this atmosphere, heating it up. Only 51% gets through to warm the earth's surface. The rest is reflected by the atmosphere, or by clouds, or by the surface of the earth. And as the surface of the earth warms up, it emits long wave radiation, and something like 90% of this gets trapped in the atmosphere. And as the atmosphere warms up, it radiates long wave radiation down onto the the earth, and out into space. Armed with these numbers, and the density and specific heat of air, I now have a very simple climate simulation model. I got some of my figures from here, and some other ones from here. runSo what did it show? At right there's a graph showing the variation of surface temperature throughout a 24 hour day. The green line shows the surface temperature on an atmosphereless earth. And the blue line shows the surface temperature beneath an atmosphere with 70% cloud cover.

The mean surface temperature of the atmosphereless earth is about 263 degrees Kelvin. This is higher than the 255 degrees predicted analytically. But I'm looking at just a patch of ground at the equator, which would be hotter than elsewhere.

And the mean surface temperature of the earth with an atmosphere is 10 degrees higher, and the mean air temperature is 29 degrees higher. This isn't too far off the 33 degree increase that seems to be generally agreed to be the effect of the atmosphere.

So my simple model shows that there does seem to be warming due to having an atmosphere. And the warming is of the right order of magnitude. It's surprised me by showing very little change in temperature of the atmosphere throughout the day, and much larger changes in the surface temperature of the earth. I'm not sure whether that's right or wrong. Certainly on a hot sunny day the surface of tarmac on the ground can get far hotter than that of the air above it. Does it get far colder at night? Perhaps that's what causes ground frosts.

But this simple model seems to be highly responsive to changing the parameters. If, for example, I reduce cloud cover from 70% to 0%, the mean air temperature shoots up by 35 degrees, because clouds are no longer reflecting solar radiation into space, and both air and ground are being warmed a lot more.

According to my model, if the clouds all suddenly vanished, and we only ever had sunny days with blue skies, the temperature of the earth would start rising relentlessly, week by week, in an endless heat wave, which would end up with air temperatures of 55 Centigrade. Everyone would be dead, including the people with the most expensive air conditioning.

I found myself thinking that the far more sophisticated climate models used by climate scientists probably show a similar sensitivity. And that climate scientists probably have a strong sense of just how much our environment could change with just a slight variation in the parameters. Like cloud cover. Or carbon dioxide. Or albedo. And that's why they're all alarmists.

And here we are, pumping out carbon dioxide and soot and stuff into the atmosphere. And changing the surface of the earth as we build cities and tarmac roads. We could be pushing the planet towards a "tipping point" of some sort, just like NASA's Jim Hansen says we are.

You become a climate alarmist the moment you've built your first computer simulation model of the earth's climate. Like I have.

Because I sure hope it's cloudy tomorrow. I want to see the sky wall-to-wall with that darling fluffy stuff.
Tags: agw
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