Today, tens of millions will applaud America's annual amateur geoengineering experiment, in which 2,500 tonnes of sulfur dioxide are injected into the troposphere in a transcontinental wave three hours long. As this aerosol extravaganza coincides with the annual low in SO2 release from the nation's major sources, heating and heavy diesel fuels (nobody much drives bulldozers or heats homes on the 4th of July) wannabe Keelings may wish to skip the fireworks, and harrow the satellite IR data stream in search of publishable climate forcing results. I think I'll observe the latest progress in spectral pyrotechnology instead.
The often wan red , violet and blue glare of old school skyrockets reflected ingredients contaminated with common salt, whose baleful yellow sodium D-line emission washed out less vivid elemental colors.
No longer- purer chemicals produce purer colors. and increased purification of pyrotechnic strontium , cesium, barium and potassium salts, and new zeolite phosphors to host them, has produced an unprecedentedly saturated spectral palette. Together with new, hotter burning.and hence more brilliant, metallic flash powders ( titanium, lanthanum and zirconium react with the nitrogen as well as the oxygen in air) this has increased the efficiency and aesthetic impact of colored fireworks as radically as LED development has improved lighting efficiency.
While US overall fireworks consumption has grown by 70% , so great is the increase in colored light emission by the state of the art 'stars', that light up the sky that the weight of mortar-launched display shells, and the amount of propellent needed to launch them, has fallen roughly 60% since the turn of the century.
Somebody should give these guys the Copley medal for having saved the nation close to a megaton of gunpowder at no cost in shock and awe.
