Clouds of the Day - Tuesday, May 9, 2023

Stratus is a layer cloud with smooth bases and tops. Stratus may cover the entire sky or form in patches but their horizontal dimensions are always much larger than their vertical dimensions.

Yesterday I took a few photos of stratus that covered much of the sky in the early morning, but cracks were beginning to form. This indicated that the layer was beginning to break up because drier air was evaporating the cloud. Drying may be caused by sinking motion from above or it can occur by mixing of drier air from below.

In the photos above the left photo is shot at the widest angle and the photo on the right is a close-up of the lower left corner of the left photo. Eventually most of the stratus evaporated. Cumulus formed as surface temperatures warmed and created updrafts. The stratus changed to cumulus because of changes in the motion of the air from sinking to rising.