Drakensberg Valley Climates

“MOTHER NATURE CAN COMFORT AND LEAD US, CAN SHELTER AND FEED US

BUT SHE DOESN'T NEED US.

MOTHER NATURE CAN CHEAT AND MISTREAT US, DESTROY AND DEFEAT US

'CAUSE SHE DOESN'T NEED US.”

UNKNOWN

Drakensberg

Valley Climates

The climate of valleys may differ significantly from surrounding flat or higher country. The two phenomena mainly responsible for this are aspect and air flow.

By aspect is meant the angle of a hillslope or valley side in relation to the sun’s rays. South of the Tropic of Capricorn the sun’s rays will never be directly overhead and any flat ground receives oblique rather than direct insolation.

This situation is modified by the angle of the slopes so that a north-facing slope may receive direct insolation while a south-facing slope in the southern hemisphere will receive even more oblique insolation than level ground. North facing slopes are drier and warmer and south-facing slopes will be wetter, cooler and sometimes steeper.

It is evident that the aspect of a hillside can have a profound effect on plant ecology, scenery and the general comfort of animals and humans. In the Drakensberg these effects are most obvious in the Little ‘Berg but, except for the retention of snow for longer periods on the south-facing slopes and gullies, appear to have a minimal effect on the ecology of the High ‘Berg.

Quite clearly not all slopes face directly north or south although most would have a northerly or southerly component. Predominantly east- and west-facing slopes, while freed from the extremes outlined above, are subject to morning-only or afternoon-only sun.

Valleys tend to be warmer in the daytime and colder at night than the adjacent highlands. This is particularly so in winter when calm nights are fairly frequent and cold air (which is denser than warm air) is able to flow gravitationally into the valleys, leaving the mountain slopes comparatively warm. This results in the phenomenon called temperature inversion where the lowest temperature are at ground level. The cool air which drains down a slope at night is termed katabatic. It then flows down the valley to be called a mountain wind. Conversely, during the day air from the relatively warm valley bottoms, being less dense, flows upslope and is termed anabatic. It is fueled in part by the valley wind.

Associated with the mountain and valley winds are larger scale regional winds called the Minza and Umzanzi respectively. These are alternate night and day flow of air off and towards the escarpment as a whole.

It is evident from the foregoing that camping alongside a stream in the bottom of a valley, while fine in summer, may be very unpleasant during winter. It is unfortunate that this is also the time of the year when water is less likely to be found higher up towards the thermal belt and individuals will have to decide for themselves how best to compromise. It is also clear that at whatever altitude one is, it is advantageous to camp on a north-facing slope. Not only will one receive the sun earlier, but at any time of the day it will be warmer than a south-facing slope.

We as hikers, explorers, and adventurers have the absolute duty to respect and protect our Wildernesses. Nobody else will do it for us. Take ownership!

The End.

Safe Hiking.