Empa analyzes "water phenomena
Using a new water channel, Empa in Dübendorf is investigating meteorological phenomena. The world is getting warmer, and cities in particular should brace themselves for rising temperatures. This forecast calls for action. But first we need to understand the exact causes and their effects.
The water channel at Empa Dübendorf is six meters long, one meter wide and 0.6 meters high. The acrylic glass corridor filled with luminous green liquid floats between two mighty blue housings that provide flow and circulation. The facility stands in its hall a few steps away from the larger wind tunnel, which has been available to Empa since 2010.
For the study of dynamic processes in the atmosphere, the new test and measurement equipment complements it. For example, the effect of buoyancy between building volumes in the water channel can be better simulated, and smaller-scale models representing a larger environment can be used.
Meterological phenomena
The movements above and between the solid mass can be detected and registered thanks to a laser measurement system: Tiny particles and a fluorescent dye are mixed into the water. The laser beam illuminates the particles - photographed by a camera that takes two pictures in succession.
The knowledge gained consists in the flow velocity and the flow direction, as it is known from aerodynamic experiments, furthermore the temperature distribution is also visible with this method.
The experiments are one of many pieces in the mosaic that the Empa research team is using to track meteorological and climatic events together with related institutes at ETH Zurich. The effect of the nature of surfaces, vegetation, shade, etc. will also be investigated. The goal is to arrive at clear, authoritative statements about natural phenomena in our environment.
The fact that the path to them is very difficult was demonstrated by short technical presentations given on the occasion of the opening of the water channel. Researchers operate with models, measurement results and simulations. The atmosphere is often difficult to delimit, and observations can provide different facts or even conceal them, depending on the level of detail or "resolution".
The general public, which finances the research and the expensive equipment, may expect that newly acquired knowledge in this field will be incorporated into the regulations of regional and urban planning. It should show us which building methods, planning concepts and outdoor space designs promote a pleasant climate at specific locations and put a stop to the waste of cooling energy.
Remarkably, the focus is strongly on heat as a consequence of climate change. Dealing with cold or drafts in urban spaces seems almost negligible in comparison.
