© Ben Clark
Lakelands, Western Australia, Australia
Latitude: 32° 28' 26'' S
Longitude: 115° 47' 3'' E
06 January 2016 1916 (Local Time)
Camera direction: towards SSE
Image I.D.: P.10.20
CL = 9, CM = 6, CH = 3
Links in the image description will highlight features on the image. Mouse over the features for more detail.
Cumulonimbus is a heavy and dense cloud, of considerable or strong vertical extent, in the form of a mountain or huge towers. At least part of its upper portion is usually smooth, or fibrous or striated, and nearly always flattened. Though the upper parts are often whitish in colour, in this case the orange glow is due to the low angle of the setting sun, which is no longer lighting the lower part of the cloud. In the photograph, the upper portion of the Cumulonimbus has the characteristic flattened, fibrous top of the species capillatus, and the top has spread out in the shape of an anvil, which is supplementary feature incus. As the origin of this cloud was a forest fire at Yarloop, some 65km to the south-southeast of the camera, we may also use the designation flammagenitus. The ash content of the lower part of the cloud is clearly visible .
A large high pressure system in the Great Australian Bight was directing ENE to ESE winds over the area.
The Perth sounding (94610) about 110 km to the north, shows a relatively moist layer below 880 hPa fed by a sea breeze and capped by a temperature inversion. At medium and upper levels the air is dry. Temperatures generated by the intensity of the forest fire were clearly sufficient to break down the inversion and allow vigorous convection to occur.
Himawari 8 channel 4 shortwave IR image. The Cumulominbus appears symmetrical with a two distinct areas of overshooting tops evident. The immense vertical extent of the Cumulonimbus can be gauged by the shadow it is casting to the ENE. Incus, the anvil shaped part of the top can be seen spreading to the SE and it is also casting a shadow to the ENE. More Cumulonimbus cells can be seen to the NE and cirriform cloud offshore.
Cumulus and Cumulonimbus forming above the King Fire, Eldorado National Forest.
Cumulonimbus generally results from the development and transformation of Cumulus.This can make it difficult to distinguish Cumulus congestus of great vertical extent from the first stage of Cumulonimbus, that being the species calvus. If any of the sprouting upper parts are indistinct and flattened the Cumulus has transitioned to Cumulonimbus calvus.
The cell on the left side has flattened and has the beginnings of an indistinct top. It is Cumulonimbus calvus, not capillatus, as the upper part does not have any cirriform parts of a clearly fibrous or striated structure.
The cell to the immediate right has sharply defined upper parts on its left side but its back right edge has a domed, just short of flattened, appearance. Cells to the right appear to be more recent Cumulus congestus that are in an earlier stage of their life cycle.
The accessory cloud pileus is superposed/above cells at 1 and 2. This feature should not be mistaken for evidence of indistinct and flattened tops that have the appearance of a whitish mass without sharp outlines.
Of interest is the cumuliform cloud has a slightly dirty appearance indicating the presence of fine ash particles through their vertical extent.