Latest News Archive

Please select Category, Year, and then Month to display items

SA now experiencing half-year summers

12 October 2020 | Story Leonie Bolleurs | Photo Supplied

Although several international studies have used temperature metrics to statistically classify their seasonal divisions, a study in which Adriaan van der Walt was involved, would be the first known publication in a South African context using temperature as classification metric.

Gone are the days when we as South Africans would experience a three-month spring season, easing into summer, and then cooling off for three months before we hit winter.

Adriaan van der Walt, Lecturer in the Department of Geography at the University of the Free State (UFS), focuses his research on biometeorology (a specialist discipline exploring the role and climate change in physical and human environments) as well as climatology and geographic information systems.

He recently published an article: ‘Statistical classification of South African seasonal divisions on the basis of daily temperature data’ in the South African Journal of Science.

In this study, which Van der Walt undertook with Jennifer Fitchett, a colleague from the University of the Witwatersrand, data on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

They went to great lengths to ensure that they had a complete set of data before presenting it to demonstrate seasonal brackets.

First for South Africa

Their statistical seasonal brackets indicate that South Africans now experience longer summers (from October to March), autumn in April and May, winter from June to August, and spring in September.

Although considerable work has been done using rainfall to determine seasonality in Southern Africa, Van der Walt believes that these methods did not work well as there are too many inconsistencies in this approach, as identified by Roffe et al. (2019, South African Geographical Journal). To make matters more complicated – as a semi-arid region, and with desert conditions along the west coast – some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study. “Temperature, by contrast, is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification,” says Van der Walt.

He continues: “Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as classification metric.”

Van der Walt says what we understand as seasons largely relates to phenology – the appearance of blossoms in spring, the colouration and fall of leaves in autumn, and the migration of birds as a few examples. “These phenological shifts are more sensitive to temperature than other climatic variables.”

Seasonal brackets

According to Van der Walt, they believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

“One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons, and so we welcome any alternate approaches,” he says.

A number of sectors apply the temperature-based division to their benefit. “For example, in the tourism sector it is becoming increasingly important to align advertising with the season most climatically suitable for tourism,” says Van der Walt.

Temperature-based division is also used to develop adaptive strategies to monitor seasonal changes in temperature under climate change. However, Van der Walt points out that each sector will have its own way of defining seasons. “Seasonal boundaries should nevertheless be clearly communicated with the logic behind them,” he says.

News Archive

UFS involved in project to light up the townships

2006-06-06

The parties involved with the project are from the left: Prof Hendrik Swart (Departmental Chairperson of the UFS Department of Physics), Dr Thembela Hillie (CSIR), Prof Neerich Revaprasadu (Department of Chemistry at the University of Zululand) and Dr Wynand Steyn (CSIR).

UFS involved in project that could light up the townships

The University of the Free State’s (UFS) Department of Physics is involved with a project that could make life easier in the townships through the use of artificial light.

“The project is based on the use of sunlight to activate nano material in for example cement and paint during the day. At night the cement or paint can then radiate light,” said Prof Hendrik Swart, Departmental Chairperson of the UFS Department of Physics.

According to Prof Swart an amount of R3,9 million has been made available by the Council for Scientific and Industrial Research (CSIR) for the further development of the project.

Prof Swart visited the University of Florida in America in 1995 for a year where he researched luminescent phosphor material that is suitable for flat panel television screens. The red, green and blue spots on the television screens originate from these kinds of phosphor materials. “At that stage plasma television screens were only a dream. Today it is sold everywhere,” said Prof Swart.

“Upon my return I started a research group at the UFS which investigated the degrading of phosphor material. We also started to concentrate on the effectiveness of nano phosphors. In the mean time our cooperation with the Americans was strengthened with follow-up visits to America of my colleagues, Prof Koos Terblans and Mr Martin Ntwaeaborwa,” said Prof Swart.

“Nano phosphors are basically luminescent powders that consist of particles that are 1 millionth of a millimetre. These particles can provide light as soon as they are illuminated with, for instance, sunlight. The amount of time these particles can provide light, is determined by the impurities in the material,” said Prof Swart.

According to Prof Swart nano particles are developed and linked to infrastructure materials in order for these materials to be excited during the day by sunlight and then it emits light during night time.

“The nano material is of such a nature that it can be mixed with materials, such as paint or cement. The yellow lines of roads can for example emit light in a natural way during night time,” said Prof Swart.

About a year ago Prof Swart and Dr Thembela Hillie, a former Ph D-student of the UFS Department of Physics, had discussions with Prof Neerich Revaprasadu from the University of Zululand and the CSIR about the possibility of mixing these nano phosphor particles with other materials that can be used as light sources in the building of roads and houses.

“Prof Revaprasadu is also actively involved in the research of nano materials. Our efforts resulted in the CSIR approving the further extension of the project,” said Prof Swart.

“The UFS and the University of Zululand are currently busy investigating ways to extend the light emitting time,” said Prof Swart.

“There are eight M Sc and Ph D-students from the UFS and about five students from the University of Zululand working on this research project. The Department of Physics at the Qwaqwa Campus of the UFS, with Francis Dejene as subject head, is also involved with the project,” said Prof Swart.

According to Prof Swart the further applications of nano materials are unlimited. “Children whose parents cannot afford electricity can for instance leave any object such as a lamp, that is covered with these phosphor particles, in the sun during the day and use it at night as a light for study purposes,” said Prof Swart.

According to Prof Swart the further extension of the project will take about two years. “During this time we want to determine how the effectiveness of the phosphors can be increased. Discussions with the government and other role players for the possible implementation of the project are also part of our planning,” said Prof Swart.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
6 June 2006

Back

Economic and Management Sciences

Education

Health Sciences

The Humanities

Law

Natural and Agricultural Sciences

Theology and Religion

Open Distance Learning

Business School

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept