Spain's largest wildfire on recordThe worst fires erupted in mid-July in Spain's Ávila and Madrid provinces and France's Gironde Department. As repeated heat waves and prolonged drought arrived during spring and summer, that vegetation dried out and became abundant fuel. The rising hot air carries smoke, ash and moisture high into the atmosphere, where it forms a towering thunderstorm-like cloud. Scientists who monitor these events said it was the first reported wildfire in France to produce such a cloud, although similar events have occasionally occurred in Spain and Portugal. NASA said satellite observations remain an important part of wildfire monitoring.