ISS No. 42-42590523
by NASA JSC/Michael Benson - © Corbis. All Rights Reserved. - © NASA JSC/Michael Benson/Kinetikon Pictures/Corbis
Complex cloud formations over the Senegalâ€"Mali border, Africa
Mali --- Complex cloud formations over the Senegal–Mali border, Africa. Cumulonimbus clouds like these can tower more than ten miles high in the tropics, only flattening, as here, when they reach the tropopause—the border between the troposphere, the lowest and densest part of Earth's atmosphere, and the high-altitude stratosphere. Mosaic composite photograph. ISS 016 Crew, February 5, 2008 --- Image by © NASA JSC/Michael Benson/Kinetikon Pictures/Corbis