A solar flare disrupted shortwave radio transmissions for half an hour in South Korea, the country\'s National Radio Research Agency says. The agency issued an alert just after 8 a.m. Friday, Yonhap News Agency reported. Solar flares, a temporary local increase in brightness, release large amounts of energy that increases the ionization of Earth\'s upper atmosphere. That disrupts shortwave, high-frequency transmissions and can also affect satellites and cause problems for astronauts. The U.S. Space Weather Prediction Center said the flare was the brightest so far this summer, Space.com reported.