You are looking at the Icelandic volcano plume from above as it continued to spew ash days after the initial eruption. The red region in this infrared image reveals the intense thermal emission of at least 60 megawatts. For more on the eruption, see Earth Observatory: Ash Plume across the North Atlantic.
Throughout mid-April, the Icelandic volcano's plume of ash traveled east into Europe's airspace, grounding flights for over a week (click on the image above to see the plume's path). You can see images of the volcano at different times in April at this NASA page. For more on volcanic activity in Iceland, check out the Physics to Go issue Dynamic Earth.