Windhoek — Away from our skies, weather patterns around the hemisphere continue to emphasize the clash between a normal or regular framework and the intervention of systems responding to the increasing influence of global warming.
Being on the sidelines does not mean that our skies had no part in these stormy events.
Such vortex patterns draw in air from places well distant from the scene of action: places as far away as the polar regions to the relatively adjacent Congo air mass.
Just about all the descriptions of weather were formulated within the Temperate climate zone of the northern hemisphere. Not surprisingly, the active weather patterns created by the clash between polar and sub-tropical air present many features requiring better definitions.
Clouds are one of these. A few of these cloud developments are identified as being found within air of, at least, sub-tropical if not actual tropical origin. The two cloud types which indicate a move from these warmer regions into cooler surroundings are Altocumulus Castellanus (one level) and Altocumulus of a chaotic sky (2 or more levels).
Relevant Links
Tropical air is moist and warm. The combination brings about instability meaning that the lapse rate, the degrees cooled as one ascends is of greater value than the normal 3oC per 1000 feet. This instability encourages the upward movement of a warmer current pushing into and through this unstable layer. The ensuing cloud development can be rapid and the probability of thunderstorm development shortly afterwards is to be expected.
Both these altocumulus cloud formations are associated with such developments. They are often given the "thundery sky" description.
These past few days, with dry air beneath, the full panorama of the sky was unveiled. Both these cloud types were present in some profusion. The visible turbulence was there for any observer to see and the almost explosive (by weather standards) genre could well be marvelled at. It gave the observer some understanding of how such an air mass (several thousand feet deep) can enable violent storms to erupt and cascade rain (hail too) to the surface.
Apart from a few heavier showers from the Summerdown and adjacent areas, the rainfall results were limited by the dry surface air and by the limited, narrow band of moist air.
What's coming
Overall, the pattern remains little changed. The upper anticyclone has reformed further east and the weak trough line lies across Namibia.
Activity will be restricted to a rather narrow band lying across the eastern parts. Middle layer moisture is there, but surface input is limited by this upper air presence: a rather typical October/November stance.
Comments Post a comment