How Much of an Effect Does Altitude and Humidity Have on the Accuracy of a Watch?

grtnev

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Jan 18, 2009
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I have been using the same gentleman to service my watches for about 20 years now and, anecdotally, I have observed that when I receive a watch back from him, it is not unusual to find, after running on my desk for at least 24 hours in the face up position, that the watch will be gaining 6-12 seconds/24 hr as opposed to being in agreement with his electronic timing machine at his location.

At my location:
  • Typical uncorrected barometric pressure: 25.10 in Hg @ 4,722 ft (1,439 m)
  • Typical humidity varies from: 30% to single digits depending on the time of the year
  • Typical temperature varies from: 23°F to 95°F depending on the time of the year.​


At his location:
  • Typical uncorrected barometric pressure: 28.5 in Hg @1518.7 ft. (462.9 m)
  • Typical humidity varies from: 20-70% depending on the time of year
  • Typical temperature varies from: 28°F to 86°F depending on the time of the year.​

Temperature variations are similar at both sites, being a little warmer (and much drier) at my location during the summer.

However, there are significant differences in the uncorrected barometric pressure and humidity variations:
  • Difference in barometric pressure from his location to mine, typically: -3.4 in Hg (-1.67 psi)
  • Difference in humidity can be as much as 60-65% higher at his location during the summer and 5-15% higher at his location during the winter.
Would these typical variations in humidity and barometric pressure from his location to mine explain why a watch would run a few seconds faster at my location as opposed to at his location; i.e. lower humidity at my location (much lower during the summer) with a lower barometric pressure?

Thanks in advance for your thoughts.

Richard
 

musicguy

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I would assume hypothetically that altitude, pressure, humidity and other factors
could effect how a watch runs. But 12 seconds a day is 1.4 minutes a week
or 5.6 minutes a month that sounds like a big error that might not
be explained by location after a complete service.


Rob
 

John Matthews

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Sep 22, 2015
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I assume the comparison is face-up in both locations. Have you asked the watch maker to run the same 24 hour test for comparison?

John
 

svenedin

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Jan 28, 2010
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You don't say what these watches are or how old they are. I would be rather pleased with an accuracy of 6-12 seconds in 24 hours.
 

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