Met Office: CH4 Cirrus progressively invading the sky

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C_H4 Cirrus progressively invading the sky

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Gallery
© R.K. Pilsbury	© Mrs M.I. Holmes
© J. Walton

Gallery

The cirrus clouds of C_H 4 are the same species of cirrus as those of C_H 1. However as C_H 4 they progressively invade the sky and generally become denser as a whole. They often seem to fuse together in the direction of the horizontal from which they have first appeared and the forward edge moves towards the opposite part of the horizon. The clouds occur most frequently in form of strands trailing from a small hook or tuft and less frequently in the form of straight or irregularly curved filaments.

Cirrostratus should not be present, otherwise the coding would be C_H =5 or 6 as appropriate.

The cirrus clouds shown in these photographs were steadily invading the sky and had an estimated base of between 20,000 and 25,000 ft.

Classification
Description: Cirrus in the form of filaments, strands or hooks, progressively invading the sky and generally becoming dense.	Designation: C_H=4 (C0)
Latin name: Cirrus fibratus (Ci fib) or Cirrus uncinus (Ci unc) [plus several varieties].

Classification

Description:
Cirrus in the form of filaments, strands or hooks, progressively invading the sky and generally becoming dense.

Designation:
C_H=4 (C0)

Latin name:
Cirrus fibratus (Ci fib) or Cirrus uncinus (Ci unc) [plus several varieties].