Crepuscular Rays and Cumulonimbus Clouds

An astronaut aboard the International Space Station took this oblique photograph of crepuscular rays while orbiting over southern Asia. The combined off-nadir perspective and low Sun angle highlight the varied cloud structures and warm hues from the setting Sun.

Crepuscular rays, named after the Latin word for twilight, are shafts of light that can appear at any time of day but are most often visible near sunrise or sunset. In this astronaut photograph, gaps between the clouds allow rays of light to penetrate through and partially illuminate regions of shadow cast by the tall clouds. Water vapor and aerosol particles in the atmosphere scatter light, accentuating the bright crepuscular rays.

These rays are known by a variety of names, including sunbeams and antisolar rays. The optical effect is often visible from the ground. However, the high-altitude perspective from the space station is distinctive because astronauts can capture a greater field of view, showing the truly vast distances spanned by the sunbeams. Crepuscular rays can also occur at night when clouds or other high-altitude features block incoming moonlight.

The clouds visible in the photo are cumulonimbus clouds formed by updrafts of warm, moist air. Cumulonimbus clouds are also called thunderclouds because they are often associated with extreme weather, such as lightning, hail, and tornadoes. The flat upper surface of mature cumulonimbus clouds, which resembles an anvil, is caused by strong winds that prevent clouds from growing upward past the tropopause—the layer of the atmosphere that forms a boundary between the troposphere below and stratosphere above.

Astronaut photograph ISS069-E-88621 was acquired on September 16, 2023, with a Nikon D5 digital camera using a focal length of 105 millimeters. It is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 69 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by Cadan Cummings, Amentum, JETS II Contract at NASA-JSC.