Skip to main content
17 votes

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

Mark's answer about mercury barometers is correct - but it is not the complete story. Barometers were initially constructed using water, not mercury, on the manometer principle. Water is lighter ...
Graham's user avatar
  • 437
11 votes
Accepted

Temperature change in Earth atmosphere models?

There's some kind of explanation about the units under the picture. The formula is based off the average temperature in degrees Celsius (measured over the entire year, and the entire Earth), which is ...
Glorfindel's user avatar
9 votes

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

A mercury barometer is a simple, easy-to-build barometer that turns the problem of calibrating a pressure standard into one of calibrating a length standard. Accuracy of length standards has long ...
Mark's user avatar
  • 1,261
6 votes

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

I don't think they are using that level of accuracy for the old readings. Reporting pressure, in hPa, to one decimal place is being done for recent measurements. There are no values given for very ...
Fred's user avatar
  • 24.7k
6 votes
Accepted

What is the atmospheric pressure at the deepest point of the Kidd mine?

From the book Environmental Engineering in South African Mines, The Mine Ventilation Society of South Africa, 1989, pp 451-455. The equation required is: $P \ = \ P_{atm}\cdot e^{\frac{-gMh}{1000R\...
Fred's user avatar
  • 24.7k
5 votes

What does a floating mercury barometer look like? How does it work and how is buoyancy used?

A good place to start would be with Fortin barometers. They were "commonly used at meteorological stations to measure atmospheric pressure". The advantages of this type of barometer are its ...
Fred's user avatar
  • 24.7k
4 votes

Do sound waves from volcanic eruptions travel around the world?

Yes, if you include low frequency pressure changes as would be recorded on a barometer as sound waves. The 2022 Hunga Tonga eruption sent atmospheric pressure waves that were detected multiple times ...
GrapefruitIsAwesome's user avatar
4 votes

When it is said that air moves from warm object to a cold object, how is it possible that air moves from high pressure area to low pressure area?

You are correct that air generally moves along the surface from high pressure towards low pressure (not directly, but deflected due to the coriolis effect). However, this does not imply that it is ...
torbjorn's user avatar
  • 101
4 votes

How closely related is surface air temperature to pressure?

You have opened a very large can of worms. You will need a larger can to get them all together again. The problem is time lag. Let's do some thought experiments: It's dawn in the desert. Right ...
Sherwood Botsford's user avatar
4 votes
Accepted

How to identify low or high pressure area

Because you specifically asked about winds and pressure, there is a fairly applicable rule of thumb. It's called Buys Ballot's Law. Basically, if the wind is to your back (coming behind you), and ...
JeopardyTempest's user avatar
4 votes
Accepted

Why does air subside in the Eye - the lowest pressure area of a tropical cyclone?

I will just talk about an already formed tropical cyclone. Converging winds spiral in (counterclockwise in northern hemisphere) over the warm ocean waters towards the central low pressure area of the ...
Dalton Bentley's user avatar
4 votes
Accepted

What causes these periodic high-pressure blobs along the west coast of South America?

It's really not clear from their website what data source those maps are showing. They could be derived purely from surface observations, purely from model output, some atmospheric analysis ...
Deditos's user avatar
  • 3,950
3 votes

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy? To compare records of barometric temperature, this standard doesn't necessarily have to be met. ...
Will's user avatar
  • 131
3 votes
Accepted

At what point is the atmospheric pressure considered to be high or low?

Usually when you hear someone say "high" or "low" pressure, it is an abbreviated way of saying "local maxima" or "local minima." And usually that pressure is ...
BarocliniCplusplus's user avatar
3 votes

Is there a relationship between pressure drop and sea level rise?

Is there really a relationship between pressure drop and sea level rise? The author of the card was writing about storms at sea. By way of analogy, think of what happens when a person with a ...
David Hammen's user avatar
  • 23.6k
3 votes

Why is the Atlantic anticyclone an area of high pressure if it's the warmest spot on the planet?

The Bermuda high is centered near the horse latitudes, where air from the tropical Hadley trade wind cell is sinking. This forced sinking of air can dynamically contribute to high pressure even if the ...
Jack Denur's user avatar
3 votes
Accepted

Can strong winds significantly lower ocean surface levels, or is it really the static pressure differences?

The explanation for the wind effect on water level at the coast is basically the same as for upwelling circulation. In an upwelling situation, the winds flow parallel to the coast and generate ...
arkaia's user avatar
  • 15.4k
3 votes

How does MSLP change with elevation? trying to interpolate MSLP

So the Mean Sea level pressure is defined (simply) as the pressure of the station, corrected to sea level. However, methodological problems occur over terrain, such as assumptions that may not be true....
BarocliniCplusplus's user avatar
3 votes
Accepted

What does the index "p" mean in the gradient of geopotential in pressure coordinates?

The subscript $p$ denotes that it on a pressure surface. It is more or less a formality for a derivation, so it is commonly dropped. It is rooted in the chain rule Put another way, it eliminates the ...
BarocliniCplusplus's user avatar
2 votes
Accepted

Why do meteorologists use DM and equal height surfaces for some maps?

First, yes, DM does appear to be decameters (though Dm would be more proper). D was actually the abbreviation I was taught for deca in grade school 20 years ago, but it appears da has become the ...
JeopardyTempest's user avatar
2 votes
Accepted

With respect to latitude and time of year, what geopotential heights are associated with low pressure systems on the North American landmass?

Great question! First, let's look at typical data: here are the 1981-2010 Reanalysis mean and standard deviation: So looks like the mean 500 height in September for Wisconsin ranges from about 571-...
JeopardyTempest's user avatar
2 votes

Pressure as a function of altitude above 11 km

There doesn't seem to be central reference for standard temperature and atmospheric pressure at high altitudes. Below is the code I wrote after combining two resources that can be found in the ...
Shital Shah's user avatar
2 votes
Accepted

How is surface pressure generally measured, and at what actual height?

When you look on meteorological maps the "surface pressure" is actually the reduced MSLP (mean sea-level pressure) value. See this NWS page for more info. So whatever height the sensor is at above ...
JeopardyTempest's user avatar
2 votes
Accepted

Estimating fracture pressure (looking for literature to support)

fracture formula What is the method of injection and fluid you are using? Apply a leak off test to the formation after drilling out casing shoe and your 5-10m into open hole. I’ve attached two links ...
Jeffrey Boettger's user avatar
2 votes
Accepted

Do high pressure systems draw air towards them?

As Fred said, it's just an unfortunate word choice that makes you think the professor is suggesting air flows towards the high. Indeed, a surface high pressure south of Sydney would be the ...
JeopardyTempest's user avatar
2 votes

Why doesn't one build pressurized camps at Mount Everest?

The Nepali government is extremely sensitive to the notion of climbing their mountains as "sport" and understand that all elements that undermine the sporting nature of climbing, ...
Knob Scratcher's user avatar
2 votes
Accepted

Confusion with thermal wind mechanism

based on the hypsometric equation, at any same level, the pressure over cold area is lower than that over warm area, resulting in horizontal pressure gradient from warm to cold area. Not necessarily. ...
mEXsACHINE's user avatar
1 vote

Air pressure on Mars below ground

The Mars Atmosphere Model web page by Nasa lists the equation for atmospheric pressure as, $P = 0.699e^{-0.00009h}$ Where pressure, $P$ is in kilopascals and $h$ is height is in meters. Rearranging ...
Fred's user avatar
  • 24.7k
1 vote

How are barometric pressure measurements traceable over centuries to 100 parts per million accuracy?

The maximum reading was taken at Aberdeen Observatory and they still have a barometer which was in use during the period the reading was taken (the inscriptions dates it to 1888 and after 1922 it was ...
Pete Kirkham's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible