Cloud Shadow Projection

July 16, 2018


Photographer: Daniel Francis 
Summary Authors: Daniel Francis; Jim Foster

The photo above shows a cumulus congestus cloud (bottom) and its projection on a cloud bank in the background. It was captured above Tampa, Florida, not long before sunset -- the camera is facing west. Projected shadows such as this one result when the cloud shadow is cast upon a thin layer of haze (dust or aerosols). Note that these types of shadows are more often observed when looking toward the Sun -- within about 10 degrees of it.

The silver lining of the cumulus congestus is due to backlighting from the Sun. This cloud is optically thick, and thus its underside and front appear dark to the viewer. However, because the edges of the cloud are relatively thin, light coming from the Sun is scattered forward. Note also the patch of iridescence at right center. Photo taken on May 30, 2018, at approximately 7:15 p.m.

Photo Details: Apple iPhone SE camera; f 2.2; 4 mm focal length; ISO 25, 1/3846 sec. exposure.