" alt="Nacreous (also known as mother of pearl or stratospheric) clouds. These clouds form at around 20km altitude in the ozone layer and are instrumental in the process of ozone depletion. Because of their altitude they remain illuminated by the sun, long after sunset on the ground.">

" alt="Atmospheric effects on the clouds seen from an aircraft flying above them.">

" alt="Sunset illuminating bands of cirrus clouds">

" alt="Lenticular alto-cumulus cloud backlit by the setting sun above Jason Peak.">

" alt="Clouds around mid-afternoon.">

" alt="Wave clouds, also known as 'stack of plate' clouds. These are formed by air being forced to rise over a mountain range, with the moister layers condensing to form cloud.">

" alt="Lenticular clouds at South Georgia, indicating lee-wave generation within the atmosphere. The waves are caused by stratified air flowing over the island. Taken from Barff Peninsula, South Georgia.">

" alt="A stack of plate clouds above South Georgia - altocumulus lenticularis - stationary wave clouds caused by airflow over mountains">

" alt="Detail of plate clouds above South Georgia">

" alt="Cloud reflections and pack ice in the Weddell Sea">