Duplicatus

Definition

A cloud variety in which two or more layers of cloud are superposed at slightly different levels, sometimes partially merged. It occurs in cirrus, cirrostratus, altocumulus, altostratus and stratocumulus.

Field note

Duplicatus is a wind-shear signature: two layers at slightly different altitudes are moving differently, which is why they can be seen as separate sheets. It often precedes a frontal passage by 12 to 24 hours.

Related terms

• Undulatus · undulatus
• Altocumulus · Altocumulus
• Cirrostratus · Cirrostratus