Wave Clouds Over Apennine Mountains, Italy42.6N 11.9E
Sediments line the Adriatic coast of Italy (right) while the western coast is mostly clear. Several rounded crater lakes are visible near the west coast in the central part of the country, the largest of which is Lake Bolsena, formed starting 370,000 years ago following the collapse of a caldera of the Vulsini volcanic complex into a deep aquifer.
Visible northeast of the lake are wave clouds, formed by atmospheric internal waves that are created as stable air flows over a raised land feature such as a mountain range, and can form either directly above or in the lee of the feature. Here, the wave clouds have formed over the Apennine Mountains.