The storm glass was popularised by Admiral Robert Fitzroy after his historic voyage on the HMS Beagle. 

How the Storm Glass works is still a mystery, but it is believed that electromagnetic changes in weather patterns activate the crystals inside (sealed glass chamber fill with crystals when air pressure decreases). 

This is a gorgeous decorative gift idea for the adult who has everything or someone who finds meteorology fascinating. 

How to read:
A: Clear Liquid
Bright and clear weather
B: Cloudy Liquid
Sometimes with small stars and crystals at the top. Cloudy weather and often predicts thunderstorms and rain.
C: Small Stars in Liquid
Humid or foggy weather
D: Large Flaky Crystals
Cloudy skies, snow in winter. 
E: Threads of Crystals At The Top
Winy Weather
F: Crystals At The Bottom,
Frost may be coming.