67% of Earth’s surface covered by clouds

Cloud cover over Earth

67% of Earth’s surface covered by clouds at any given time. Cloud cover is especially dominant over the oceans where less than 10 per cent of the sky is completely cloud free at any one time. On average only 30 per cent of land surface is cloud free. NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) map shows cloud free areas appearing dark blue; moderate cloud cover appearing light blue; and frequently overcast areas are white.