Stormglass

They have been around for many years (as the report says) often mounted on a mercurial barometer.

I have no idea how/why it works but it certainly does move from cloudy to clear and seems to reflect something to do with the weather (again, as the report says).

Rather a curio nowadays (give me a synoptic chart in preference).

I have not checked but you might pick one up at a store such as Nauticalia.

Tom
 
They do provide some information - the critical bit about changing pressure. However what really matters is the shape of the changing pressure to get the proper information. I now gain this electronically, but a barometer is better than nothing.
 
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