The snow-covered Popocatepetl volcano spews a cloud of steam into the air in Puebla July 9, 2013. Mexican authorities raised the alert level for the Popocatepetl volcano on Saturday after an increased level of explosive activity belched ash over Mexico City and pushed international airlines to suspend flights.The alert level for the towering Popocatepetl volcano, located some 50 miles (80 km) to the southeast of the capital, was raised to yellow phase three from yellow phase two, Mexico's National Center for Disaster Prevention said in a statement. [Photo/Agencies]