On page 49 of Bad Astronomy, it describes a seasonal temperature change due to the ellipticity of the Earth's orbit as 4-degree Celsius. Handily, that is converted into Farenheit, for us metrically-challenged Americans, but it says it is "roughly 6 degrees Farenheit." That's a bit small, as 4 degree C is (x 9/5) 7.2 degree F, but it's probably close enough.

However, the next sentence describes the seasonal change in Maine as 30 degree Celsius, which is converted to "80 or so degrees Farenheit". That's quite a bit high. 30 C is (x 9/5) 54 degree F, which is pretty close to the seasonal differences for Portland, Maine shown at these websites.

Hmmm... I may have simply converted 80 degrees to Celsius, which is not the right way to do a difference. An 80 degree swing is roughly 44 C, not 30. Nuts.

That difference may be a bit high anyway; I would think 70 is closer, but I won't quibble too much. From people I know who live in Maine, 54 degrees sounds too low for the temperature swing. Portland is on the water and has its climate mitigated by the ocean. Inland is worse.

I think the formula to convert degrees Celsius into degrees Fahrenheit is ºF=9/5ºC-288/5.

ºF=9/5ºC+32

ºC=5/9(ºF-32)

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T. Anderson

F = 9/5C + 32. Water freezes at 0ºC (32ºF) and boils at 100ºC (212ºF).

However, when you're talking changes, it's simply F = 9/5 C. 0-100ºC is a 100º change and 32-212ºF is a 180º change. 180 = 9/5 * 100.

So, 30ºC = 86ºF, but a difference of 30ºC is a difference of 54ºF.

Confusing enough? [img]/phpBB/images/smiles/icon_smile.gif[/img]

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SeanF

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The contents of this post are ©2008 by SeanF and may not be copied or retransmitted in any form without the express written consent of SeanF

GoW was converting the difference of two temperatures, so the addition constant of 32 goes away:

Tc1 - Tc2 = 5/9 * (Tf1 -32 - (Tf2-32))

which equals

Tc1 - Tc2 = 5/9 * (Tf1 - Tf2)

<font size=-1>[ This Message was edited by: The Bad Astronomer on 2002-03-07 14:19 ]</font>

Certainly agree with that:
http://www.unidata.ucar.edu/staff/blynds/tmp.html#Dev

I didnt realise Celsius was an astronomer [img]/phpBB/images/smiles/icon_smile.gif[/img]
http://www.astro.uu.se/history/Celsius_eng.html

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You are all right, I wrote the formula the other way around. It should have been ºC=9/5ºF-288/5. And I hadn't realized that you were thinking of differences.

[Hadn't noticed that I had posted the same thing twice. Now I can't delete it. Perhaps the BA can do it?]

<font size=-1>[ This Message was edited by: informant on 2002-03-08 04:20 ]</font>

Seasonal temperature deltas of 54ºF? In Colorado, we get daily temperature deltas of 54ºF.


<font size=-1>[ This Message was edited by: Wiley on 2002-03-07 15:10 ]</font>

Well, sure. I'm from Wyoming, lived in Colorado for a few years.

Those Portland, Maine, links seem to show that an average temperature for July is 68F, and the average for December is 22F, so the difference is 46F. BA thought it would be more, away from the shore.

I do have another error to report. It's a typo. On page 134, it says a meteroid velocity of 100 kilometers per second converts to 80 miles per second. I know it's the publishers fault because the conversion is right (impact crater of 10 kilometers is 6 miles) on p.138.

I saw the formula for temperature conversion misused in the same way in one of Cliff Pickover's books as well, although I don't recall which one. I guess it's an easy thing to do.

Reading this thread made me realise how much simpler it'll be for you Americans when you go metric.

[img]/phpBB/images/smiles/icon_biggrin.gif[/img]

(Peter B - Proudly metric since 1974)

It would be simpler still to give up on this metric fad. How long can it last anyway?

informant,
Would you please explain where you get the term "-288/5"?

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Simple explanation: I got it from my rusty rusty dumb old brain.
Yes, the formula I typed was utterly wrong. I won't even try to correct it anymore. I'm too afraid that I will write more nonsense.
Well, back to first grade...

World record for temperature change:

January 22, 1943, Spearfish, SD - at about 7:30am, the temperature rose 49ºF (from -4ºF to +45ºF) in two minutes. Broke windows all through town. By 9:00am, it was up to 54ºF. Then, the temperature dropped back down to -4ºF, with the 58º drop taking about 27 minutes. Blamed on a "chinook wind."

The saying in SD is, "If you don't like the weather, just wait five minutes - it'll change."

[img]/phpBB/images/smiles/icon_smile.gif[/img]

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SeanF

"Ask to understand, but don't challenge unless you have the knowledge."--NEOWatcher

The contents of this post are ©2008 by SeanF and may not be copied or retransmitted in any form without the express written consent of SeanF

Oof! That's a shock: 49 degrees in 2 minutes. Well, that is if I believed you ...

We all know that South Dakota doesn't exist, it's just story invented by the government. Sure, I know you say you're from Souix Falls, but that just proves you're part of the conspiracy.

I know this isn't the proper forum, so I won't give proof here. I got a book coming out about this. For only $29.95, you can have an advance copy.

Personally, I think everyone should skip the Fahrenheit and stick to Celsius and SI units in general. American students are behind the rest of the developed countries in the world in mathematics and science largely because they have stuck too long to these antiquated methods in calculating.

I never discuss anything in English units (if possible). However, when I am driving, I guess I have to go with the units which are shown on the road signs and on my speedometer (which also has very tiny metric units which cannot be seen).

However, look what happened to the mixup of units at JPL (where the engineers were using metric) and the other company's engineers (not to be named) who were using English. In this country at so many universities, English is taught to engineers. Dumb...

Oh, well, Bad Astronomer Phil, the important measurements in your book are the metric units. I would never have noticed. English units are such a waste of time and effort.

OH, YES, GREAT BOOK!!!

ljbrs [img]/phpBB/images/smiles/icon_biggrin.gif[/img] [img]/phpBB/images/smiles/icon_smile.gif[/img] [img]/phpBB/images/smiles/icon_wink.gif[/img]

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I have always been for the metric system, but since I moved to a country that uses it exclusively, I simply cannot understand why it hasn't been at least partially adopted in the US. It took a bit of time to get the hang of it and start thinking in metric units (a bit like learning a new language actually), but once I did, it has become so much easier to deal with than the cumbersome old british system.

I may never be 100% fluent in metric units, but they really aren't hard to get used to if you are immersed in them.

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As an engineer in the US, I have had to deal with unit conversions for years. In the mid-70's, there was a concerted effort to convert all engineering to metric; it failed, btw.

However, I saw and bought a poster promoting the conversion. It was printed in Germany (a metric country) and shows two young women - one 20ish, the other 10ish - in swimsuits. Under each is her measurements in centimeters, 36-24-36 and 102-61-102... a take on the "perfect" 36"-24"-36" figure.

I've kept the poster all these years for two reasons (neither one in a swimsuit, you perverts!). One is the little girl with her "perfect" metric figure. The other...

Well, see if you can "figure" it out.

Lessee, Rounded to the nearest inch, 102-61-102 is 40-24-40, not 36-24-36.

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T. Anderson