SUNSET.
(Alto-cumulus Castellatus Fractus.)
Plate 33.
SUNSET.
(Alto-cumulus Castellatus Fractus.)
CHAPTER V
LOWER CLOUDS
The clouds of the lower portions of the atmosphere are formed in regions where water vapour is abundant, and frequently in easy reach of the strong ascending and descending air currents produced by the varying temperatures and irregular surface of the ground. It is sufficient to recite these conditions to show that these lower clouds will be denser, larger, coarser in texture, and characterized by greater definiteness of form than those we have, so far, considered.
In the International system they are classified thus—