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Written by John Olszewski
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The timing, start and end, of our rainfall season have at
least two sides. While late rains, May or even June, can often be linked to the
weather patterns of the autumn, the ensuing rainfalls will have no value to the
growth of that previous season. The environmental people, from both
agricultural and conservation side advise that such rain benefits the soil
levels as a measure of preparation for the forthcoming season. The sun’s
altitude rises in the sky from July onwards, so the ability for photosynthesis
process to use available moisture becomes more and more favourable; so July
enters the stage as a consideration from the sunlight angle.
Thus far we have had since 2000, 6 years during which the
rainfall pattern across Namibia has varied from passable to excellent. By the
end of the individual rainfall year, the disaster stories are difficult to find
in our normally arid context. To quote Mr. Frans Bester, “distribution is
absolute” when attempting classify any or one rainfall season. In arid
climates, distribution across the key months, the core months of the rainfall
season, can go badly awry. Drought and all the unpleasant attributes will occur
and recur in the “normal” season.
So with the threshold of the new season in the offing, the
question must be “can this passable to excellent pattern continues?”
In the opinion of this weather observer, the response varies
from “Why not?” to a more positive “Yes”.
The cards on the table feature the increasing warmth (in
effect across the globe) to the effects which such warmth is likely to have on
our local weather pattern, also the historical factor of favourable recurrence.
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Written by John Olszewski
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What happened?
Across much of the country, the serene passage of
winter pursued its sunny way. Daytime temperatures basked in the mid-twenties,
nights were understandably chilly, but the overall experience lacked the harsh
bite of winter. The south lies closer to the expected action arena of a
Southern Hemisphere winter; this last week may not have been as amiable as the
northern and central region experience.
Temperature is the weather factor of which we are most
readily aware. For much of mankind this factor determines whether mankind makes
a home in a given area or not: being warm-blooded our range of temperature
tolerance is distinctly limited. Fortunately, the weather patterns across much
of the planet provide considerable areas where this temperature range fits our
make-up.
Across much of the country, we are used to an amiably
warm range of temperatures. In hilly country, the variation of temperature
between hilltops and valleys can be distinctive. Windhoek has provided a
classic example. The first weather station opened on a site beyond the northern
limits of the town in 1891.
These amateur enthusiasts did well. But the town grew
in all directions. After the First World War, the new Meteorological Assistant,
Mr. E. Zelle, found his weather station beset by urban growth.
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Written by John Olszewski
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What happened?
From one aspect, the arrival of “winter” is just about
complete. The likely tendency for pleasantly warm days (from at least 10 AM
through to 4 PM) and chilly to cold nights (from 6 PM to about 8 AM) is
fulfilled on a daily basis across the northern and central interior.
The southern third, being closer to the temperate zones and
thus on the northern end of active cold front activity experiences mild to warm
daytime temperatures, colder days (maximum temperatures in the mid-teens) last
for just on a day.
A further renewal of the positive aspect has been the
presence of Cirrus ice clouds. These ice particle clouds are generally so thin,
their vertical extent can be less than 100 feet (30 metres) so much so that
they presence cannot be detected in a radiosonde ascent.
The patches of Cirrus cloud Tuesday during daytime were
about 1000 feet thick. This observation notes the Sun's appearance when the
cloud patch lies between the observer and the Sun giving the “frosted glass”
aspect of unclear outlines. This description is usually noted when thin
Altostratus is present (also a rare cloud type in our skies).
The turbulence shown by the Cirrus cloud was equally interesting.
The turbulence is caused by lateral, rather than vertical motion. The Cirrus
level winds vary between the 60-knot ranges to in excess of 150 knots. This
speed excess is turbulent at any time.
The other aspect is of expectation but unfulfilled expectation.
This aspect concerns the absence of rain in the far south, at least. This
southern area receives rain, according to the climate records and the history
of occurrence on a regular basis. By Namibian standards, this rainfall
expectation is the most reliable in the country.
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Understanding Weather 
