Past and Future Forecasts

Meteorology still depends on a bit of clairvoyance, but in the 19^th century many sailors, fishermen, and farmers "had to rely on storm glass, an inexpensive and profoundly inaccurate divining tool." The mixture of "camphor crystals, potassium nitrate, ammonium chloride, water and alcohol" transitions from "solid to crystalline under circumstances that still aren't full understood." Frank Swain has details and pictures on SciencePunk, along with an account of the origin of forecasting in the British Isles. On Class M, James Hrynyshyn considers the complicated effects of clouds on world climate. James writes, "most of the greenhouse effect is related to water vapor," but with a fixed amount of H₂O in the water cycle, only the addition of CO₂ to the atmosphere can provoke global warming. As for the clouds, "more clouds could cool the Earth by reflecting more sunlight. But it is also conceivable that more clouds could trap more heat." And on Greg Laden's Blog, a NASA project yields a detailed map of global ocean salinity. Greg writes, "Ocean salinity is important because it is linked to the overall climate system. For instance, where evaporation is high, owing to atmospheric conditions, salinity goes up." Makes us wonder about the 700-year forecast.

• Storm Glass: the mysterious weather-predicting fluid crystal on SciencePunk
• Surprise! Clouds have a cooling effect on Class: M
• Aquarius Yields NASA's First Global Map of Ocean Salinity on Greg Laden's Blog