Sunrise, Earth Limb

STS052-23-022 (22 Oct.-1 Nov. 1992) --- As the Space Shuttle Columbia orbited Earth in an easterly direction over the Indian Ocean, moonrise was followed quickly by sunrise. The photograph was taken from an altitude of 285 kilometers (154 nautical miles), over Lake Tanganyika in central Africa. The Sun was still 28 degrees below the horizon and not yet illuminating the dark band of low-level clouds on the limb 1,850 kilometers (l,000 nautical miles) away. Ranging from 13--18 kilometers above these low-level clouds is a brown layer at the tropical tropopause. A tropopause is a major atmospheric temperature inversion which isolates the troposphere from the stratosphere and effectively concentrates particulate from both above and below this level.