After 9-11 we noticed an immediate improvement in the color of the blue sky which became vivid, saturated and absent contrails and haze, when all air traffic was halted.
The air cleared at the Beijing Olympics, getting better through the course of the games as traffic was halted, and on the last days, the skies were the clearest anyone could remember.
In the last four days of this April week, high altitude air traffic over the Northeast is reduced due to the Iceland volcano and cancellation of flights to parts of Europe. Today we witnessed the same vivid blue skies unlike any we have seen since 9-11. No contrails or haze, just fluffy white clouds among a perfect blue. We saw people with their eyes skyward.
Air travel has become more expensive, uncomfortable, crowded and unpleasant. One can imagine a time in the not-too-distant future when the price of oil is about $250 a barrel, and an air ticket to from London to Boston is about $2500.
How blue will the sky be then?