Authors: Prof. Dr. Philipp Weihs, Prof. Dr. Josef Eitzinger, Ing. Wolfgang Laube
Basic concept of the building block
The following experiment, which can be carried out on various homogeneous paved surfaces, demonstrates the influence of shade on outdoor ground surface areas. Students should be able to understand the differences between the radiation balance of a shaded area and that of a sunny area, as well as be able to measure and quantify these phenomena.
Description of the building block
This building block contains directions for the completion of the experiments listed below. A description of the basic conditions, which must be met in order to complete them, is also included. The experiments demonstrate the influence of shade conditions on the energy balance and the effects of shade on ground surface temperature.
The measurements quantify the spatial and temporal dynamics of energy flows in our environment and can be carried out over a time period of one day (cloudless conditions are necessary).
The temporal variability of the energy balance components and radiation balance is examined with the help of measurements from a two-component net radiometer, which separately measures shortwave radiation (albedo) and long wave radiation (upward and downward flows). The two-component net radiometer is mounted on a tripod.
Using this device, measurements of the radiation balance can be taken in the shade (of an object or building) and in the direct sun. The measuring device is moved from one location to the other every ten minutes and vice versa.
In order to be able to clearly differentiate between the two sites in the data, the camera should be covered with an opaque cloth one minute before changing positions.
The temporal variability of the radiation balance measurements is additionally analyzed using fish-eye images (horizontal constraints, shade conditions). The horizontal constraints and the shade conditions of the individual locations are defined and modeled using the fish-eye images and with the help of the software program Hemiview. The data recordings are taken with a Campbell datalogger. The online visualization of the data can be carried out with a laptop and measuring software from Campbell.
The various radiation flows in the shade and in the sun are quantified. Surfaces around the Exner and Gregor Mendel buildings and the BOKU trial site in Groß-Enzersdorf are well suited for the trials.
The building block is divided into four steps:
Step 1: Directions for conducting the experiment
Step 2: Setting-up the experiment
Step 3: Conducting the experiment
Step 4: Analyzing and interpreting the data
Course materials include:
- Short instructions to the building block
- Recommendations for implementing the building block into the course
- Bibliography and links