Smoke and haze along cold frontal boundary
A cold frontal boundary was moving southeastward through the Great Lakes region on 02 August 2007; Terra MODIS true color imagery (above) showed a very hazy air mass along and ahead of the advancing frontal boundary, with a very clean air mass behind the front. The dew point temperature at Madison, Wisconsin dropped from 70º F to 42º F in the 24-hour period following the frontal passage. Also evident on the MODIS image is a thin light-colored streak (oriented southwest-to-northeast) across northeastern Wisconsin, which was the damage path from a long-track tornado that occurred nearly 2 months earlier on 07 June 2007.
The IDEA MODIS aerosol optical depth (AOD) product several days earlier (below) revealed a high AOD signal (orange to red enhancement) over the northern Rocky Mountains region, due to thick smoke from numerous wildfires that were burning in Idaho and western Montana. Much of this smoke was subsequently transported eastward along the cold frontal boundary (MODIS AOD image Java animation).
