The sheer magnitude of the destruction in Tuscaloosa, Ala., is difficult to comprehend until you are here and can see street after street reduced to rubble — homes, stores, warehouses, parks. President Obama acknowledged the scope as he toured some of the areas hardest hit by this week's storm."
Last April, a volcanic eruption in Iceland sent a cloud of ash billowing towards Europe. That ash was potentially hazardous for aircraft, and authorities decided to ground all flights — inconveniencing tens of thousands of travelers — rather than risk an accident.
Although images of dead birds and blackened marshes in the Gulf of Mexico are gone, many scientists say it's too early to declare a recovery. They suspect there could be hidden damage to the Gulf's marine life and marshes.