Talk:Hygrometer

varying quality

this company sells about 9 different hygrometers. Can anyone account for why the different units show somewhat different humidity percents? The readings generally diverge from each other by approximately 5 percent points. I've seen 7% difference once. Nastajus 07:14, 19 August 2006 (UTC)

technically challenging

Humidity measurement is one of the more challenging technical problems in basic physics, mainly because small microclimate variations from place to place make it nearly impossible to maintain a consistent RH throughout the environmental chamber used for calibrating the devices. Two thermometers can be compared by immersing them in an insulated vessel of water and stirring vigorously to minimize temperature variations within the container, but air is many orders of magnitude less efficient as a heat-transfer medium (just compare the cross-sectional area of the pipes used to distribute heat from the furnace in a house with hot-water heating to the cross-sectional area of the ductwork used to distribute heat in a house with forced-air heating!). Unless one wishes to purchase highly-specialized equipment costing thousands of dollars, the most accurate means available to most of us for humidity measurement is a good-quality wet-dry psychrometer. Actually if a bunch of cheap digital devices are all within 5 percentage points of each other they are doing rather better than is typical of such devices! 71.235.75.86 11 August 2007

Well a year later I got my answer! Thank you. They sat in a row next to each other, 1 foot apart. Perhaps the humidity would be really different at the other end of the store, away from the doorway. I've added the ip reference, for whatever it's worth. Nastajus (talk) 04:26, 8 June 2008 (UTC)

It's possible to directly measure changes in the permittivity of air due to humidity changes with a pair of closely spaced electrodes as a capacitor. It's not necessary to have the vapor absorb into some media used as a dielectric. Changes in humidity are seen almost instantly. And the changes are a fair amount larger than those from inserting a 1 mil plastic film between the electrodes. --Aflafla1 (talk) 03:53, 28 July 2013 (UTC)

Pix

Does anyone have a picture of a chart recording Hygrometer? Preferably the kind with two pens: red for temperature and blue for humidity? RJFJR 18:59, 3 October 2005 (UTC)

There are already three images of hygrometers on this page. How many do we really need?  :-) Tim Pierce 05:19, 7 December 2005 (UTC)

Coil type

Info on the metal(s) in a coil hygrometer would be good (there's already a picture of one). I bought some (non-adjustable) coil hygrometers and they appear to be extremely inaccurate, but I recall an accurate one from childhood.

I added a bit of info. One tip for gaining an accurate one that (surprisingly) worked for me: I went to a store when the temperature and humidity was fairly low (dewpoint in the upper 40's Fahrenheit) in the fall and selected one based on the known humidity that day, assuming that indoor and outdoor dewpoint were the same. I have it in my basement and I also have an electronic sensor down there and they are usually within ~3% of each other. The electronic sensor was checked in salt chambers at 33% and 75% and it was within 2% at those points. These two in my basement are usually closer than two identical electronic ones I have, so I might have just got lucky ;) --Ron E (talk) 15:10, 26 August 2011 (UTC)

Calibration

Is this calibration info good? If folks think it is, let's add a link or adapt it for use in the article.

WikiProject class rating

This article was automatically assessed because at least one WikiProject had rated the article as stub, and the rating on other projects was brought up to Stub class. BetacommandBot 09:54, 10 November 2007 (UTC)

digital

There's lots of cheap digital hygrometers now available from places that sell consumer electronics. Are they any good? Are they basically the capacitive type described in the article and do they mostly obsolete the other types? Should there be more space devoted to them in the article? 207.241.239.70 (talk) 06:42, 24 January 2009 (UTC)

You would probably get a better answer at the WP:Reference desk. However, as a quick answer, we seem to have problems with our digitals at low temperatures, −20 °C (−4 °F) and colder, reading too low, and these would not be cheap ones. CambridgeBayWeather Have a gorilla 11:14, 24 January 2009 (UTC)

I propose adding something to section about psychrometers

How do people feel about my adding the following to that section of the article?

"The dry bulb constitutes one of the two thermometers in a sling psychrometer. The other is called a sock. The person using the sling psychrometer covers the sock with water before putting the instrument into motion. In order to get a reading, the user slings (swinging it causing the two thermometers to rotate) the sling psychrometer. During the slinging, the water on the sock evaporates."

Here is the source: p. 308, Barron's Earth Science The Easy Way by Alan D. Sills. Hauppauge, New York: Barron's Educational Series, Inc., 2003.

I shall wait several days. If no one shares a reaction here, then I hope to add the passage to the section about psychrometers.Earththings (talk) 05:03, 9 December 2009 (UTC)

There is a sentence about sling psychrometers already there. By the way does the book really call the wet-bulb a sock? I've never heard it called that before. We call it a wet-bulb, (see Wet-bulb temperature) and the muslin sleeve that goes over it at below freezing temperatures is the sock, until it gets too cold and then we just make ice. But getting a nice even ice coating on a sling is a real pain. Enter CambridgeBayWeather, waits for audience applause, not a sausage 07:08, 9 December 2009 (UTC)

Yes, it does call the wet-bulb a sock.Earththings (talk) 03:07, 14 December 2009 (UTC)

Humidistat

Searching the term humidistat, a device analogous to a thermostat but which responds to humidity not temperature, redirects to humidifier. A humidistat should have its own entry, but at least it should redirect to here, not humidifier. Many modern microwaves utilize a humidistat in "smart cooking" applications such as microwavable popcorn. Darqcyde (talk) 15:12, 8 September 2011 (UTC)

Application

There is a sentence at the end of the paragraph that states "These devices make measurements a lot faster but are often not allowed in explosive environments.". Does anyone have a reference to backup this information? DevRockinAZ (talk) 08:31, 18 December 2014 (UTC)

The preceding sentence states "With a growing demand on the amount of measurements taken the psychrometer is now replaced by a dewpoint gauge known as a dewcheck." I could not find any information on what a "dewcheck" is, other than a particular meter with the brand name "DewCheck". This appears to be an inappropriate product placement, but I myself don't have enough knowledge to be certain. 70.68.217.153 (talk) 02:56, 27 January 2017 (UTC)

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Spectroscopic Chilled Mirror Citation Required

In the "Chilled Mirror Dew Point Hygrometer" section the second paragraph currently reads:

More recently, spectroscopic chilled-mirrors have been introduced.^[3] In this techniques, the dewpoint is detected using a spectroscopic detection, ascertaining the nature of the condensation. This method avoids many of the pitfalls of the previous chilled-mirrors and has been shown to be able to operate drift free.

I would like to request two edits to be made to this paragraph. These are:

1. Removal of the company name reference at [3]. I believe that this may be in breach of covert advertising guidelines. The company name returns more prominent search results (the top result) from www.google.co.uk than searches for "Spectroscopic Chilled Mirrors" thus giving the company an unfair competitive advantage as indicated in the covert advertising guidelines.

2. Add the requirment for a good quality citation of the claims made in the paragraph at its end. As of the time of writing this request the only information I have found regarding "Spectroscopic Chilled Mirrors" is related to the company referenced at [3].

Thank you in advance for considering these edit requests.

Aegir1984 (talk) 19:35, 19 September 2017 (UTC)

(1) – agreed, the whole point of a reference is to give a source for Wikipedians to check information accuracy, just giving a company name is not specific enough. (2) – I am confused what you are requesting. Are you asking me to find a citation for this paragraph, or do you wish it to be labeled [citation needed]? Altamel (talk) 16:54, 20 September 2017 (UTC)

Hello Altamel,

Thanks for looking at this editing. The second part is just for adding a [citation needed] label as the only information sources I can find have been authored by the CEO of the company in question without suitable peer review or independence of opinion.

Aegir1984 (talk) 10:12, 25 September 2017 (UTC)

RH

What does mean RH ?

Thanks.

--AXRL (talk) 23:04, 7 November 2017 (UTC)

ok found : Relative Humidity...

--AXRL (talk) 23:12, 7 November 2017 (UTC)

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Problem with the test: above the frost point

The article includes the following sentence:

However, a conventional hygrometer is unable to measure properly above the frost point, and the only way to go around this fundamental problem is to use a heated humidity probe.[8]

I have zero expertise on this subject, but I think it should read "below the frost point" - can someone please check it and either correct the article or correct me?

Thanks

Gravimetric Hygrometer

I've rewritten the explanation to match the cited paper—the process compares the weight of a desiccant before and after using it to dry the gas sample, then calculates the amount of dried gas from its temperature, pressure and volume. The principle is to determine the amounts of water and gas separately, not to compare the weights of humid and dry gas as originally stated. I've also cited an NIST page which says this explicitly. Musiconeologist (talk) 03:23, 16 February 2023 (UTC)

Short description

The Android app didn't give me the opportunity to leave an edit summary when I changed this. So this is the edit summary. I've changed "relative humidity in the atmosphere" to "humidity", since it needn't be either atmospheric humidity or relative humidity which is measured. Musiconeologist (talk) 19:53, 18 February 2023 (UTC)

Weird edit summary

I accidentally saved today's edit (March 6th, 2024) part way through writing the edit summary. It was a reversion of the previous edit, and Undid revisby . . . should read Undid apparent spam by . . . Musiconeologist (talk) 20:26, 6 March 2024 (UTC)