WRAL WeatherCenter Blog

Beautiful Blue Sky

Posted May 13, 2008

Did you notice how blue the skies were this morning?  I sure did.

One of our New Media photographers, Ricky Leung, snapped these pictures near the WRAL Azalea Gardens, showing these blue skies behind some green grass and gorgeous flowers.

Under normal circumstances, the skies generally appear blue thanks to how sunlight is absorbed and scattered in the atmosphere.  Blue light has a shorter wavelength, which tends to scatter more effectively than longer wavelength light when we have a "clean" atmosphere. 

When we have a lot of humidity or pollution in the atmosphere, though -- like we often do during the summer months -- that changes the equation.  Those particles are larger and tend to scatter all wavelengths of light more effectively, resulting in a lighter blue or even a white-ish sky, especially close to the horizon.  (Since most of those particles tend to hang close to the ground, that effect is more noticeable low in the sky -- but we can still see some blue directly overhead.)

So, why all the blue today? 

In a nutshell, we've really maxed out the "clean atmosphere" concept I mentioned above.  The rains of the last couple of days have helped to wash the atmosphere clean of all the pollutants that had accumulated.  We've also begun to draw in much drier air from the northwest, especially aloft.   Both of those factors tend to "deepen" the blues in the sky colors we see.

The blue skies and fantastic weather will stick around for a couple of days, so try to get out and enjoy it while it lasts.  One way to enjoy the weather in the next couple of days is to pay a visit to the WRAL Azalea Gardens, here on Western Boulevard in Raleigh. The best part: they're free and open to the public!

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