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Early equinox!

Discussion specific to Fine Offset and similar rebadged weather stations
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Mortello1
Posts: 22
Joined: Mon 03 Mar 2014 2:13 am
Weather Station: Maplin N96GY
Operating System: Windows 7 (64 bit)
Location: Ireland

Early equinox!

Post by Mortello1 »

On my display for March 18, sunrise is given as 6.42 and sunset at 18.44, giving a day length of 12.02. This is presumably incorrect since we haven't even got to the equinox yet 8-)
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beteljuice
Posts: 3292
Joined: Tue 09 Dec 2008 1:37 pm
Weather Station: None !
Operating System: W10 - Threadripper 16core, etc
Location: Dudley, West Midlands, UK

Re: Early equinox!

Post by beteljuice »

It's not always when you think ;)

Check out for your location here: http://www.timeanddate.com/worldclock/a ... =-11&day=1
Image
......................Imagine, what you will KNOW tomorrow !
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steve
Cumulus Author
Posts: 26672
Joined: Mon 02 Jun 2008 6:49 pm
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Location: Vienne, France
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Re: Early equinox!

Post by steve »

http://en.wikipedia.org/wiki/Equinox
An equinox occurs twice a year (around 20 March and 22 September), when the plane of Earth's equator passes the center of the Sun.
[...]
Another meaning of equinox is the date when day and night are the same length.The equinox is not exactly the same as the day when day and night are of equal length for two reasons. Firstly, because of the size of the sun, the top of the disk rises above the horizon (constituting 'sunrise' which is the start of 'daytime') when the center of the disk is still below the horizon. Secondly, Earth's atmosphere refracts sunlight which means that an observer can experience light (daytime) even before the first glimpse of the sun's disk has risen above the horizon. To avoid this ambiguity the term equilux is sometimes used in this sense. Times of sunset and sunrise vary with an observer's location (longitude and latitude), so the dates when day and night are of exactly equal length likewise depend on location. For places near the equator the daytime is always longer than the night, so they would never experience an equinox by this definition.
Steve
Mortello1
Posts: 22
Joined: Mon 03 Mar 2014 2:13 am
Weather Station: Maplin N96GY
Operating System: Windows 7 (64 bit)
Location: Ireland

Re: Early equinox!

Post by Mortello1 »

You learn something new every day, thanks guys :)
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