Cumulonimbus Anvil Over France

September 23, 2010

Photographer: John Caswell; John's Web address
Summary Author: John Caswell; Jim Foster

The photo above featuring a huge cumulonimbus cloud with an astonishing anvil was taken during a flight somewhere over France on July 11, 2010. When conditions are optimal for developing storms, a single cell thunderstorm will on occasion shoot into the upper reaches of the atmosphere and even into the lower stratosphere. The flattened anvil indicates that at this altitude the storm cell is no longer buoyant in relation to the ambient atmosphere. It's likely at the tropopause. The height of the tropopause varies with the season. In mid-latitudes, an average height might be 7.5 mi (12 km). However, it's altitude is typically higher toward the tropics and lower toward the poles.

Note that while the surface is rather dark, the cloud itself is basking in sunlight. It's high enough to still be illuminated by the Sun, which has set at the surface.