Cloud Formation Chart

Clouds appear in a variety of pure and transitional forms. This chart gives a "grapenuts", concentrated, description of the factors that determine which of the l2 major cloud forms will be present at a given moment under a given set of circumstances.

A particular cloud is determined by the stability of the airmass in which it appears, the amount of positive (upward) buoyancy , or negative, in the airmass, the water vapor content, the temperature range, the presence of uplift due to fronts (cold, warm, occluded) and physical barriers (hills and mountains).

The information below the chart clarifies the meanings of the symbols e.g. under airmass stability uuu means very unstable, uu means somewhat unstable, etc.; under buoyancy +++ means very buoyant, ++ means somewhat buoyant, etc.

Cloudman's Cloud Formation Chart
Group	Elevation	Name	Airmass Stability	Buoyance Convection	Moisture Content	Temperature	Frontal Lift	Orgraphy	Precipitation Type
Heap	High	CU congestus	uuu	+ + +	L	+	C.F.	Y	sh
	Middle	CU swelling	uu	+ +	M	+		Y
	Low	CU fair weather	u	+	S	+
Layer	High	CS	s	0	S	-
	Middle	AS	s	0	M	+	W.F.		r
	Low	ST (Fog)	ss	0 (-)	S	+			m
Heaps and Layers	High	CC	u	+	S	-
	Middle	AC	u	+	M	+
	Low	SC	u	+	M	+
Precipitating	High	CI	N	0	S	-			sh virga
	Middle	CB	uuuu	+ + + +	LLL	- +	C.F.	Y	shshshsh
	Low	NS	u	+	MM	+	O.F. W.F.		rrr
Description Code for Each Column Above
	CU Cumulus		S Stable N Neutral U Unstable	+ up   - down	S Small M Moderate L Large	+ above freezing - below freezing	W.F. warm front C.F. cold front O.F. occluded front	Y yes	sh showers r rain m mist
	CS Cirrostratus
	AS Altostratus
	ST Stratus
	CC Cirrocumulus
	AC Altocumulus
	SC Stratocumulus
	CI Cirrus
	CB Cumulonimbus
	NS Nimbostratus