Barometer and thermometer

[Le_Jars]

Do any of you know where I might be able to buy a digital barometer and thermometer, combined if possible? Thanks 

[Pierre ZFP]

My local Auchan has a large selection from fairly cheap (around 20 Euros) to amazingly expensive.

 

[Cassis]

They're enormously popular.  No French home appears complete without one.  Most large supermarkets (like Pierre's Auchan) and DIY places such as Mr Bricolage, Bricomarché usually have a selection.  Also Mr Outiror and the other lorries.

[Le_Jars]

Many thanks, I didn't realise they'd be so easy to find!

[Cassis]

Yes - that's why all the French are such experts on the weather! 

[Cassis]

Here's a whole bunch of them online in case your local shops have sold out!

Weather stations

Prices vary wildly - I assume you generally get what you pay for.

At the bottom of the page there are some on e-bay as well.

[Le_Jars]

Hmmm.... I need one that I can stick in the river here (I want to track

it's temperature throughout the year) and I don't see one where I can

do this. Perhaps I just have to get an ordinary thermometer which can

be stuck anywhere (arf!) and a seperate barometer. I've tried a medical

digital theremometer but the range is very small (as in dead to high

fever!), so no good for water that gets down to almost freezing!

[Cassis]

Well, now you've thrown a curve ball!  Why do you want to put a barometer in the river?  I can see you might want to know the temperature, if you're fancying a dip, but atmospheric pressure?

[powerdesal]

Maybe le_jars is a closet Desalination plant designer???????

[Cassis]

Come on, Dave, what are you up to?

[Le_Jars]

It's all very simple......I want to stick the thermometer in the river

to test it's temperature (obviously) and I want to know the barometric

pressure (not by sticking it in the river, cos there's no need) cos I

want to know the pressure innit?

This is all in the name of fishing. I understand I can catch more fish

when the pressure is high and the temperature is low enough (for trout).

[Cassis]

Okay - sounds reasonable!

Here are some thermometers for fishing and I would suggest one of the weather stations already mentioned for your barometer.

[Le_Jars]

See! I'm not mad!

Many thanks for that - I'll see if my local peche/chasse shop has something like those. Thanks again.

[Dick Smith]

An old, long story, apologies if you have heard it before:

"A question in a physics degree examination at the University of Copenhagen ran thus:

"Describe how to determine the height of a skyscraper with a barometer."

One student replied: "You tie a long piece of string to the neck of the barometer, then

lower the barometer from the roof of the skyscraper to the ground. The length of the

string plus the length of the barometer will equal the height of the building."

This highly original answer so incensed the examiner that the student was failed

immediately. He appealed on the grounds that his answer was indisputably correct, and

the university appointed an independent arbiter to decide the case. The arbiter judged

that the answer was indeed correct, but did not display any noticeable knowledge of

physics. To resolve the problem it was decided to call the student in and allow him six

minutes in which to provide a verbal answer which showed at least a minimal familiarity

with the basic principles of physics. For five minutes the student sat in silence,

forehead creased in thought. The arbiter reminded him that time was running out, to

which the student replied that he had several extremely relevant answers, but couldn't

make up his mind which to use.

On being advised to hurry up the student replied as follows:

"Firstly, you could take the barometer up to the roof of the skyscraper, drop it over the

edge, and measure the time it takes to reach the ground. The height of the building can

then be worked out from the formula H = 0.5g x t squared. But bad luck on the

barometer." Or if the sun is shining you could measure the height of the barometer, then

set it on end and measure the length of its shadow. Then you measure the length of the

skyscraper's shadow, and thereafter it is a simple matter of proportional arithmetic to

work out the height of the skyscraper. "But if you wanted to be highly scientific about it,

you could tie a short piece of string to the barometer and swing it like a pendulum, first at

ground level and then on the roof of the skyscraper. The height is worked out by the

difference in the gravitational restoring force T = 2 pi sqr root (l / g).

"Or if the skyscraper has an outside emergency staircase, it would be easier to walk up it

and mark off the height of the skyscraper in barometer lengths, then add them up." If

you merely wanted to be boring and orthodox about it, of course, you could use the

barometer to measure the air pressure on the roof of the skyscraper and on the ground,

and convert the difference in millibars into feet to give the height of the building.

But since we are constantly being exhorted to exercise independence of mind and apply

scientific methods, undoubtedly the best way would be to knock on the janitor's door and

say to him 'If you would like a nice new barometer, I will give you this one if you tell me

the height of this skyscraper'."

The student was Nils Bohr, the only Dane to win the Nobel prize for Physics.

[Cassis]

[:D] [:D]

So you could equally well use several of those methods to measure the height of the building with a thermometer.

I don't think I have heard that one before.  Did they still fail him for being a smarty-pants?

PS I confess that my first thought was to drop it off and measure the time it took to reach the bottom!

[Le_Jars]

So I can go fishing and measure the height of buildings! Fab! I love France, don't you?  [:D]

[Cassis]

I do indeed.  And I love your new paintings.  Sigh.  Once I had money and could afford these things - but equally, I never had time to appreciate them or life in general!

[Deimos]

Oregon Scientific do a weather sensor system (the WMR 918/WMR928 I think http://www.ukweathershop.co.uk/acatalog/oregon_scientific_cw_sub.html). Its quite expensive (£350'ish) and includes most sensors you would be interested in EXCEPT the river temperature one. It includes temperature, rainfall (cumulative and rate), wind, temp (inside and outside), pressure, etc. Most sensors are RF linked to the base and have solar cells to keep their power going (i.e. true cordless). There is an optional extra sensor to the system that is a swimming pool temperature sensor. This is a floating temperature sensor that measures water temperature (again with its own solar cell and an RF link to the base station, the THWR288 on http://www.ukweathershop.co.uk/acatalog/oregon_scientific_was_sub.html). Depending on how fast the river is flowing you may be able to anchor/tie this swimming pool sensor to the bank/a rock which might provide you what you are looking for.

The base station can also be connected to you PC and can be used to record long term weather data, publish your weather data to the internet (your own weather site e.g. http://www.tamworthweather.org.uk/wxflash.htm) or publish to one of the central weather recording systems via METEARS format (e.g. to Weather Underground).

Not cheap and maybe far more than you were looking for but it might do the temperature measurement etc. you are looking for.

(Sorry, you'll have to cut and paste the links if you are interested in them)

Ian

[Dick Smith]

[quote user="Cassis"][:D] [:D]Did they still fail him for being a smarty-pants?

[/quote]

No, they passed him.

He was a great lateral thinker.

Bohr donated his Nobel (gold) medal to Finnish war relief at the beginning of the Second World

War. Soon after the War began he was entrusted with the medals of the German

physicists Max von Laue (1914 laureate) and James Franck (1926). Before he escaped

from occupied Denmark in 1943, Bohr, a meticulous man who was known to write drafts

of postcards, dissolved the medals in acid in order to get them safely out of the country.

After the War, he precipitated the gold from the acid, and had the medals re-cast.

[Le_Jars]

Thanks Ian, but yes, that does far more than I need (and is just a tad more than I was going to pay!), but thanks anyway.