Uma nuvem cúmulo-nimbo sobre a África. Correntes convectivas levam umidade e causam o surgimento de tempestades com desenvolvimento vertical importante, atingindo mais de 12 km de altura, embora possuam curta duração. Nota-se o seu tamanho em comparação com as nuvens cúmulos ao seu redor.
English: A cumulonimbus cloud over Africa, common in tropical latitudes year-round and during the summer season at higher latitudes. ISS Crew Earth Observations: ISS016-E-27426IdentificationMissionISS016 (Expedition 16)RollEFrame27426Country or Geographic NameAFRICAFeaturesPAN-LARGE THUNDERSTORM ANVILCameraCamera TiltHigh ObliqueCamera Focal Length400 mmCameraKodak DCS760C Electronic Still CameraFilm3060 x 2036 pixel CCD, RGBG array.QualityPercentage of Cloud Cover26-50%Nadir What is Nadir?Date2008-02-05Time15:10:24Nadir Point Latitude13.5° NNadir Point Longitude-12.0° ESun Azimuth228°Spacecraft Altitude179 nautical miles (332 km)Sun Elevation Angle47°Orbit Number761Original image captionCumulonimbus Cloud over Africa Perhaps the most impressive of cloud formations, cumulonimbus (from the Latin for “pile” and “rain cloud”) clouds form due to vigorous convection (rising and overturning) of warm, moist, and unstable air. Surface air is warmed by the Sun-heated ground surface and rises; if sufficient atmospheric moisture is present, water droplets will condense as the air mass encounters cooler air at higher altitudes. The air mass itself also expands and cools as it rises due to decreasing atmospheric pressure, a process known as adiabatic cooling. This type of convection is common in tropical latitudes year-round and during the summer season at higher latitudes. As water in the rising air mass condenses and changes from a gas to a liquid state, it releases energy to its surroundings, further heating the surrounding air and leading to more convection and rising of the cloud mass to higher altitudes. This leads to the characteristic vertical “towers” associated with cumulonimbus clouds, an excellent example of which is visible in this astronaut photograph. If enough moisture is present to condense and heat the cloud mass through several convective cycles, a tower can rise to altitudes of approximately 10 kilometers at high latitudes and to 20 kilometers in the tropics before encountering a region of the atmosphere known as the tropopause—the boundary between the troposphere and the stratosphere. The tropopause is characterized by a strong temperature inversion. Beyond the tropopause, the air no longer gets colder as altitude increases. The tropopause halts further upward motion of the cloud mass. The cloud tops flatten and spread into an anvil shape, as illustrated by this astronaut photograph. The photo was taken from a viewpoint that was at an angle from the vertical, rather than looking straight down towards the Earth’s surface. The image, taken while the International Space Station was located over western Africa near the Senegal-Mali border, shows a fully formed anvil cloud with numerous smaller cumulonimbus towers rising near it. The high energy levels of these storm systems typically make them hazardous due to associated heavy precipitation, lightning, high wind speeds and possible tornadoes.