Most of the US has cloud cover today or snow cover. Air quality is generally good except for a few pockets of isolate moderate PM readings. Most of the elevated readings are from Iowa through to Maryland in the overnight hours. Low boundary layer heights and combustion don't lead to mixing. The remote sensing data doesn't show whether this is smoke or SO4 =.
So because of a lack of bad air to show, I've found some clear scenes that are pretty. On the left is a snow covered region in Arkansas, on the right, cloud streets over the Gulf of Mexico and last week's show shrouded Grand Canyon is now mostly melted but the canyon still stands out.
Update: Sunday December 30, 2012 10:00 EST
Sunday has presented the east with high winds which has definitely cleared the air. Areas of moderate PM air quality can be found in Wisconsin and Illinois (AIRNOW loop, lower left). On the right, the MODIS AQUA RGB image shows that the skies are clear in that region but the surface is mostly snow covered. There is a brownish tinge to the image but it is likely that this is the surface showing through the snow.
Posted by Ray Hoff at December 29, 2012 10:42 PM