Cumulonimbus Cloud over Africa Perhaps the most impressive types of clouds are cumulonimbus. These dynamic clouds form when warm, moist, and unstable air vigorously rises in the atmosphere. If sufficient atmospheric moisture is present, water droplets condense as the air mass encounters cooler air at higher altitudes.
As water in the rising air mass condenses and changes from a gas to a liquid state, it releases energy and further heats the surroundings, which further intensifies the convection process and causes the cloud to rise to an even higher altitude. An example of one of these vertical “tower clouds” is visible in the astronaut photograph included above. If enough moisture is present to condense and heat the cloud mass through several convective cycles, a tower can rise to altitudes of approximately six miles (10 km) at high latitudes and to 12 miles (20 km) in the tropics. The cloud formation process stops its upward convection when it encounters 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. When the cloud formation reaches this atmospheric layer, the cloud tos flattens and spreads into an anvil shape, as illustrated by this astronaut photograph. The photo was taken from a side angle, rather than looking straight down towards the Earth’s surface. The image was taken over western Africa near the Senegal-Mali border. The image 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 speed,s and possible tornadoes.
Himalayan Landscape The above photograph of Bhutan, taken by one of the Expedition 33 crew members aboard the International Space Station, shows a number of Himalayan peaks, glaciers and lakes.
Michigan, U.P., and Grand Marais Photos When you go to the NASA website I list at the top of this posting, you can type in any location on earth into the search box. The chances are that there is a photo in the archive. There were many dozen pictures listed for Grand Marais. Below I've included a few. Look for the Grand Sable Dunes and Sable Lake. The pictures were taken from different angles -- so for you GM faithfuls, have fun examining the perspectives.