baromenter/altimeter when stationary/moving

1. ## baromenter/altimeter when stationary/moving

Quick question, is it safe to assume I'll get more accurate readings with the following combinations:

when moving/hiking - use altimeter
when stationary/same altitude - use barometer
compass - any time

I'm in the south and it rains quite a bit here. I like to keep my barometer as the main function, but I do commute between Columbia and the northern part of the state and the readings are different.

How do you use your ABC features?

2. ## Re: baromenter/altimeter when stationary/moving

Welcome to the forum I'm down by Lake Murray. I have a few Casio ABC' I almost always keep my ABC's on the Baro graph to show the trend and to keep an eye on on the graph to see if the pressure drops. The altitude readings will never be stationary as they take their readings based off the Baro graph. Casio ABC do not have baro or altimeter lock other brands do.

Search the WUS for comments from members hiker and cal.45 for posts on ABC watches that have alti and baro lock.

Which ABC do you have? Or is your question a general one?

3. ## Re: baromenter/altimeter when stationary/moving

Originally Posted by bgalakazam
Quick question, is it safe to assume I'll get more accurate readings with the following combinations:

when moving/hiking - use altimeter
when stationary/same altitude - use barometer
compass - any time

I'm in the south and it rains quite a bit here. I like to keep my barometer as the main function, but I do commute between Columbia and the northern part of the state and the readings are different.

How do you use your ABC features?
Both are just barometres. The altimetre is simply using the barometric height formula to estimate the height, under the assumption that the weather and thus base pressure has not changed.

To use both successfully is the very basic of hiking and mountaineering, first have a look at the barometric height formula [1] and make sure you understand it.

The more difficult part is using it while hiking. Here it is important that weather related pressure drops happen on a relatively slow timescale, 6 mb over 3h is a very fast pressure drop. That pressure difference is equivalent to about 50 m height difference at sea level.

To be able to check atmospheric pressure for weather measurements you need reference points, i.e., a good map.* At the start of your tour you set your altimetre to the correct reference height. Then identify other reference points at your route, when you reach them compare the altimeter readings with the reference. When you overestimated the reference values it indicates that it is likely that low-pressure weather is coming.

*I understand that this can be difficult in the south, especially Columbia.
[1] https://en.wikipedia.org/wiki/Barometric_formula