Artificial Thermals

Artificial thermals may be produced by a large artificial source of heat. Here a group of three power stations close together are sending up thermals and forming small cumulus clouds. High up in the sky is the remains of an artificial cloud of ice particles formed in the exhaust of an aircraft.

Inversion

An inversion or stable layer becomes clearly visible on a clam morning when the warm dusty gas from a large chimney rises up to it but is not warm enough to penetrate it. Any slight wind then carries the plume off to one side at the level of the inversion.

Wave Clouds

Wave clouds are common at sunrise but often disappear on sunny days at inland places and return again in the evening. The nearest cloud is composed partly of billows.

Billows

Billows look rather like waves but if watched carefully are seen to be moving along at about the same speed as the wind. These are formed in a thin layer of cloud and may be termed altocumulus because they are due to convection in the layer which is far from the ground.