  We identified and computed the horizontal wavelengths of atmospheric gravity
waves in clouds using a visible camera installed on a window of the Columbus
module of the International Space Station (ISS) and controlled by a Raspberry
Pi computer. The experiment was designed in the context of the Astro Pi
challenge, a project run by ESA in collaboration with the Raspberry Pi
Foundation, where students are allowed the opportunity to write a code to be
executed at the ISS. A code was developed to maximize the probability of
capturing images of clouds while the ISS is orbiting the Earth. Several
constraints had to be fulfilled such as the experiment duration limit (3 hours)
and the maximum data size (3 gigabytes). After receiving the data from the ISS,
small-scale gravity waves were observed in different regions in the northern
hemisphere with horizontal wavelengths in the range of 1.0 to 4.7 km.
