File:Wildfire Smoke Stretches over North America (MODIS).jpg

English: Since early May 2023 wildfire smoke has repeatedly shrouded much of the Northern Hemisphere, the result of a particularly ferocious wildfire season that has been highlighted by exceptionally large fires in eastern Russia and record-breaking fires in Canada. Fierce blazes have also erupted in the United States and Mediterranean countries, lending additional smoke to the atmosphere.

According to Copernicus Atmospheric Monitoring Service, from January 1 to July 31, accumulated carbon emissions from wildfires across Canada total 290 megatonnes. This is already more than double the previous record for the year as a whole and represents over 25% of the global total for 2023 to date.

On August 1, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of a massive river of smoke stretching from across northern North America and diving southward to reach the Atlantic Ocean off the coast of Maryland and Delaware in the United States.

In the eastern half of the continent, the smoke is easily visible and mixes with cloud only in a few locations. In the west, however, it is more difficult to see the gray smoke due to the heavy layer of white cloud. In a larger image viewable on the NASA Worldview App, the smoke under the western cloud layer appears to continue to extend westward and meet with smoke flowing eastward out of Russia.

Because this image is a mosaic, created by joining together several swaths of data collected by MODIS on its repeated orbits around the Earth, several artifacts—features that appear in the image but were not in the original imaged object—can be seen. The triangular black areas at the edges are areas where no data was gathered at the edge of a swath of data. Long lines appear where two swaths are joined together to create a single image. And the silver-toned shimmer in the lower part of the image which is aligned on a nearly north-south axis is “sunglint”, which is an optical phenomenon that occurs when sunlight reflects off the surface of water at the same angle that a satellite sensor views it. The result is a mirror-like specular reflection of sunlight off the water and back at the satellite sensor.