Author Topic: Dew point decimals  (Read 340 times)

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Offline dport

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Dew point decimals
« on: June 19, 2018, 10:19:49 AM »
This is a terribly dumb question, but I can not find an answer anywhere using the search feature.  How do I get my uploaded VP2 data to report the dew point in decimals?  I've noticed that other Davis units on WU and pwsweather are reporting out to the tenths decimal place.   

Offline Bushman

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Re: Dew point decimals
« Reply #1 on: June 19, 2018, 10:29:41 AM »
Which HW (WLIP, USB etc.) and which software (Weatherlink, Cumulus, etc.) and direct or via say, Meteobridge vs. PC?

Offline dport

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Re: Dew point decimals
« Reply #2 on: June 19, 2018, 10:32:16 AM »
Which HW (WLIP, USB etc.) and which software (Weatherlink, Cumulus, etc.) and direct or via say, Meteobridge vs. PC?

Ah, ok. Its logger and software dependent. I am using the new WiFiLogger to upload directly to multiple sites.

Offline johnd

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Re: Dew point decimals
« Reply #3 on: June 19, 2018, 10:37:35 AM »
No offence to anyone, but Dew Point reports to 0.1deg, especially in F, are really displaying that the user doesn't understand what they're reporting (that is, if the software in use allows any control over the reported precision). Dew points are calculated from temperature and RH, each of which has their own error - these errors compound up when calculating dewpoint and the resulting values are typically not accurate to better than 1-2F, if that. So the decimal part of any such dewpoint value is essentially meaningless.
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Offline dport

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Re: Dew point decimals
« Reply #4 on: June 19, 2018, 10:45:48 AM »
No offence to anyone, but Dew Point reports to 0.1deg, especially in F, are really displaying that the user doesn't understand what they're reporting (that is, if the software in use allows any control over the reported precision). Dew points are calculated from temperature and RH, each of which has their own error - these errors compound up when calculating dewpoint and the resulting values are typically not accurate to better than 1-2F, if that. So the decimal part of any such dewpoint value is essentially meaningless.

No offense taken. Without the tenths place it can make for a jagged graph, but thats simply an optical opinion. Was more curious since all the Davis stations in my area report the decimal. 

Agree with you though.

Offline WiFiLogger

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Re: Dew point decimals
« Reply #5 on: June 19, 2018, 04:55:01 PM »
WiFiLogger firmware don't calculate a dew point. This value is in LOOP2 data, which is available in console firmware 1.9+.

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As you can see in Davis manual. Dew Point is in whole F degree.
Wind speed has scale 1 mph and won't be better.
Also soil temp and extra temps have 1 F scale

WeatherLink is calculating a dew point, because at the beginning there were no LOOP2 data.
« Last Edit: June 19, 2018, 04:57:28 PM by WiFiLogger »

Offline Mattk

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Re: Dew point decimals
« Reply #6 on: June 19, 2018, 05:15:25 PM »
Where one would be seeing Dew point with decimals is with averaged data values, simply a function of averaging not anything to do with precision

Offline mcrossley

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Re: Dew point decimals
« Reply #7 on: June 20, 2018, 02:54:11 AM »
Where one would be seeing Dew point with decimals is with averaged data values, simply a function of averaging not anything to do with precision
Or a result of unit conversion without appropriate rounding being applied?
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