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. Clear liquid: Bright and clear weather. Cloudy liquid: Cloudy, possible thunderstorms rain. Small dots in the liquid: Humid or foggy weather. Large flaky crystals: Cloudy skies, snow in winter. Threads of crystals at the top: Windy weather. Crystals at the bottom: Frost may be coming. Size: approx13 x 11 x 5 cm