Print Friendly and PDF

Observing Clouds

Middle-level cloud classification aid

(Section 2.8.4.2)

Click here to download middle-level cloud classification aid

						Start

Ac cas, Ac flo C_M 8 cas: turrets arranged in lines. flo: cumuli form tufts.	Yes		No		Yes
		No		Yes		No
Ac+As, Ac+Ns C_M 7 Ac together with As or Ns in one or more levels; Ac can be below or above As, Ns.	Yes			Chaotic sky C_M 9 Broken cloud sheets of Ac and others at different levels.
		No
Ac cbgen, cugen C_M 6 Flattening of cloud tops occurring when cloud grows into a stable layer.	Yes			As tr C_M 1 Reveals the position of the Sun or the Moon; no halo phenomena.	Yes
		No				No
Ac invading the sky C_M 5 One or more thin cloud layers in bands.	Yes			As op C_M 2 Dens As hiding the Sun and the Moon.	Yes
		No				No
						Ns C_M 2 Usually continuous precipitation occurs.

				Ac du C_M 7 Thin or thick patches or sheets.		Ac op C_M 7 Thick patches or sheets.
				Yes		No
Ac len C_M 4 Smooth lenticular elements at one or more levels.	Yes		No		No
						Yes
						Ac tr C_M 3 Patches or sheets at a single level.

Figure 12. Cloud classification aid C_M

« Previous Next »

The text enclosed in grey-shaded boxes, like this example, comprises Annex I to the Technical Regulations (WMO-No. 49) and has the legal status of standard practices and procedures.