Barometric Pressure: When did it become MB's?

Mee | Me

[PROCON]

When the Heck did the weather people quit reporting on the barometer? I remember how important the barometric pressure was to the weather folks, but now they're hardly touching on it, and are reporting it in millabars? I still have a wall thingy that shows the temperature, the humidity AND THE BAROMETRIC PRESSURE starting at about 28 and going to about 32. Low numbers meaning bad weather, higher numbers meaning nicer weather. Am I crazy or has anyone else noticed this too. Sheesh, maybe I have too much time on my hands, but just saying.....

[Jack Hydrazine]

You got it right.

[HippyLoggerBiker]

I, also, live in Oregon.

That Weather thingy that you have hanging on your wall will give you an idea of the weather to come.

It doesn’t really matter what it says (calibration not needed). What really matters is the amount of change. I keep a daily log with the high/low temps, amount of rain in the last 24 hours, and barometetric pressure (by my scale). After a few decades in my present location, I can, actually, out-guess the professional weather-guessers.

Wish the best to you.

[Loud Mime]

I worked with the Air Weather Service for a few years, some in Germany.

Some things were coded in meters, some in feet. Weird. Altimeter settings were reported in ins, because of he US altimeters. Visibility was meters, clouds were in feet. Temps in celsius. We had a mercurial barometer that was in MB’s.

When sending up weather balloons, we reported in MB’s.

I’m still mixed up, but can run well with the metric droppers.

[Robert A Cook PE]

Thank you sir.

[Loud Mime]

Good point about the conversion to sea level. It’s important, and I forgot about that.

[pigsmith]

I remember back in grade school, when they started trying to teach us the metric system, which up until then, had not been taught in U.S. public schools before. The teaches were very insistent that we had to learn the metric system, because it was what they used in Europe. Even then (mid-1970's), at 10 or 11, we were all like, "Whatever. Who gives a crap what they use in Europe? I'll worry about that when/if I go there."

The school was pushing the metric system when I was in third grade. Teacher said not to worry too much about learning quarts and inches and so on because soon we'd be converting to the metric system.

That was back in 1963.

[HippyLoggerBiker]

Sorry, forgot to mention:

A “Milli-Bar” is a unit of atmospheric pressure equal to one thousandth of a bar. Standard atmospheric pressure at sea level (around 14.7 lbs/square inch) is about 1,013 millibars.

You are right, the local weatherman rarely mentions barometric pressure. They just talk about a “High” or “Low” pressure system moving through the region...blah, blah, blah.

Again, wish you well.

[tsomer]

Thanks for your input.

Now my question, but first one final tangent:

I’m a woodworker and do marquetry. I use veneers that are .6 and .3 mm s in thickness, and I dye these to assure color permanence. I have a vacuum pump that will pull around 24” of mercury and sometimes I use that to force the dye all the way through the wood. I hate the noise that pump makes,so I’ve adopted another method.

The new method involves quart mason jars 3/4 full of dye,into which I plunge the veneer. Then I put the jar in the microwave to heat the dye. Once the dye is boiling I put the lid on it and screw the ring tight and take everything out of the kitchen (I always do this when the wife is out). Then I stash the sealed jars and forget about them for a few hours.

When I return to my jar stash, they’ve cooled to room temp and created a vacuum that infuses the veneers with the dyes. This method is just as reliable the vacuum pump.

I’ve been trying to figure out how much vacuum pressure is in those jars once the water cools to around 70f. I know some of it is caused by the liquid, but most is due to vapor condensation— in other words, the 8 ounce empty volume is creating most of the vacuum.

Would anybody care to take the time, or suggest where I could find the info? Yes, I ought to know this, but I was probably asleep that day in school...

[larryjohnson]

Both:
http://www.srh.noaa.gov/data/obhistory/KNRB.html

[Jack Hydrazine]

Good question. You’re pulling 24” Hg of vacuum and then allowing it cool which will increase the vacuum but by how much?

You need the GayLussac Law for the answer.

The expression Gay-Lussac’s law is used for each of the two relationships named after the French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though it is more usually applied to his law of combining volumes, the first listed here. The first law relates to volumes before and after a chemical reaction while the second concerns the pressure and temperature relationship for a sample of gas often known as Amontons’ Law.
http://en.wikipedia.org/wiki/Gay-Lussac%27s_law#Pressure-temperature_law

Pretty easy to figure out once you know the boiling temperature where you live.

[BitWielder1]

Average atmospheric pressure at sea level is 1013 mb.
Higher is high, lower is low.
Mystery resolved.

[cpdiii]

The metric system is far more logical than a system based on the length of a long dead English man's foot. However as mens feet are not uniform it may be a different measure in the next village or shire or country. As Spock would say, “That is not logical.”

See link below:

http://en.wikipedia.org/wiki/Ancient_Roman_units_of_measurement

The basis of the meter is as below: Spock would say, “This is logical.”

http://www.surveyhistory.org/the_standard_meter1.htm

If you really want confusion follow the link below to the basis of the pound weight.

http://www.dozenalsociety.org.uk/history/poundhist.html

How about grams? one cubic centimeter of water at standard temperature and pressure. That easy!

The sooner the English system of measurement and weight and temperature is confined to the dust bin of history the better. The French do not do much right but when it comes to weights and measure they got it right.

Miles per hour is just as insane. However, knots per hour is logical as it is based on one minute of arc measured at the equator. Unfortunately I think we are stuck with 360 degrees as the units for the earth and when it comes to time the insane idea hours minutes and seconds. A logical measure of time would be a ten hour day with each hour repesenting 2.4 of our present hours and each hour of that ten hour day split into 100 minutes and each minute to consist of 100 seconds. They would be called deci-hours and milli hours.

The French screwed up when it came to the measurement of temperature as the concept of absolute zero did not exist. Actually absolute zero can not be measured due to the fact of measuring it would then involve the Heisenberg uncertainty principle and the act of measurement would change the temperature of the object being measured. That aside I assure you it is damn cold.

Also aside zero should be zero on the Kelvin scale which is minus 273 degrees Celsius. A logical unit of scale would be
zero kelvin to zero Celsius defined by 0 to 100. Thus 100 units from absolute zero to the freezing point of water and this would involve no phase changes.

Spock would approve!

Some years ago we had a Mars probe that missed the planet or perhaps hit the planet instead of going into orbit. The reason this happened is an error in conversion from English to Metric in the calculations of the trajectory and entry to orbit and subsequent landing on Mars. The probe performed perfectly as programmed. It was programmed with garbage units of measurement and speed. “Garbage in Garbage out.”

Our space program blew many tens of millions of dollars due to an archaic method of measuring distance and speed.

Spock would not approve!!!

However the absolute best and logical systems of weights, distance and temperature would be based on the angstrom unit which is the diameter of a hydrogen atom and the weight of the hydrogen atom and the heat required to raise the temperature of hydrogen from zero to freezing point of hydrogen in units of 100 from absolute zero to the freezing point of hydrogen thus avoiding phase changes.

Time is a little more difficult, as our present time is based on the time it takes the earth to rotate about the sun. A logical basis of time would be the half life of tritium. The unstable isotope of hydrogen.

Using hydrogen as a basis of weight, distance and time is uniform throughout the universe. If we ever receive a signal from another intelligence in the universe its will be based on this. I would rather hope they preface their signal with a few dots that represent the number of fingers they have, if they have fingers. It would be a shame to interpret the signals as base ten when they were base 4 base 6 base 8 base 12 etc.

Did I mention that I do not like our system of measurements?

Captain Kirk: “Warp 12 Mr. Sulu.”
Mr. Sulu: “Captain, how many Angstroms is 1 Warp.”
Captain Kirk: “Ask Spock.”
Mr. Sulu muttering to himself: “Idiot, one day the Enterprise will be mine and Spock's.

[Yosemitest]

It's the United States Citizens buying the crap that the European "Metric System" is better, which it ain't.
They can take their "Metric System" and shove it where the Sun don't shine.
Don't bend to their will.
Shove the "Society of Automotive Engineers" (SAE) in their face.
The metric system robs the U.S. of jobs and power.
Most stupid Americans gave up the fight many years ago.

[Kenny Bunk]

Jack, you should live in Europe, where the Weather Nazi gives you the info according to the Scale of Torricelli. Very important as it will affect fuel consumption of Panzer units transiting the Fulda Gap.

[Ophiucus]

Just because someone calls something “international” doesn’t necessarily make it so. In the USA, it’s called the metric system.

And frankly, the bar is not “SI”; it’s actually considered deprecated by those scientists.

In this case, it absolutely makes it so. The metric system which developed during the 18th and 19th centuries was not uniform. Not only was the length of a meter not standardized and there were errors in determine its length but there were a variety of units all considered "metric" used to describe the same thing.

This was solved by selecting six base units from which all measurements could be standardized and similarly, it was agreed what defined those base units. A seventh, the mole, was the last added in 1971.

All scientists in all nations use SI units for publication and communication. That makes it, by definition, very international.

Furthermore, if you read the thread, I was not addressing bars or Pascals as a measurement. I was answering the question as to what SI units are.

[Ophiucus]

“Why won’t we adopt the metric system?” he asked—”beacause we don’t like it. Why won’t we cooperate with the federal government’s efforts to get us to use it? Because we don’t want to.”

I was, and am in full agreement.

Back in 1999, NASA lost a Mars orbiter because someone at Lockheed was using English units while JPL was using SI units. This caused a failure in navigation data. The orbiter went off course.

This is why it was so important to adopt a standardized system across all nations and languages. The data will always be understood. You don't need to use it in the supermarket but it is a necessity in accurate communication in science.

[Rodamala]

I could work this out for you... if I had all the unknowns... which h there are many.

An easy model would be to assume that the gas in the mason jar is 100% saturated steam at 212 degrees F. After capping the jar, the steam cools and condenses to a liquid.

I the thing to consider is the unknowns... like... what is the actual mix of air and steam... what is the actual temperature of the gas... the liquid... what gas volume is lost when the lid deform inward... how does the volume of the jar change when cooled?

How about we just accept that it works and have a beer instead?

[laker_dad]

How about attaching a vacuum gauge to one of the mason jar lids?

[trebb]

Millibars are SI units. 1 millibar = 0.0295333727 inches of mercury. Your old one is in inches of mercury. SI is a little more accurate but overall functionally the same. I haven’t noticed the weather idiots talking about millibars but then again once they signed on to AGW I stopped listening to them and now read my own maps from intellicast.

Takes me back to Europe and Italy in particular. Air pump gauges used mercury and were very accurate.

[Fiji Hill]

This is why it was so important to adopt a standardized system across all nations and languages.

The metric system is far from perfect. For one thing, there's no metric equivalent of the pound, foot, fathom, cup or pint. The names of most metric units have four syllables while American units have only one or two.

If a standardized system across all nations and languages is needed, maybe we should insist that the rest of the world adopt the American system of weights and measurements.