To reduce this risk, to avoid possible economic damage and safeguard the jobs of the more than 380 employees from the region over the long term, more than 10 years ago Obstland Dürrweitzschen AG decided to purchase six hail protection guns. “After the last severe hail storms we were no longer able to market up to 60% of the harvest from the affected plantations,” says Tina Hellmann, press liaison for Obstland Dürrweitzschen AG. The invention of the hail protection cannon dates back to the 19th century. Today it is mainly used by winemakers and fruit growers in southern Germany, Austria, France, South Tyrol, Spain, Holland and Belgium.
Hail occurs when evaporated water rises with the warm air. The water vapour cools and forms into droplets and clouds are formed. The water attaches to particles that are already present in the air. Together they rise to very high altitudes, where ice crystals are formed. Through gravity, they sink back down, all the while collecting more water droplets. The interplay between air currents and gravity leads to a circulation of ice crystals, in which they keep on growing.
Vertical pressure waves
The hail protection cannon interrupts this cycle by vertical pressure waves at 15 second-intervals. These pressure waves are generated by the explosion of an acetylene-oxygen mixture. As a result, water droplets cannot form into ice or hailstones so that they fall to the ground as rain or wet snow. For this principle to work, the hail protection cannons must be activated in time. Therefore, the fruit farmers are warned from approaching bad weather by a weather service. On the basis of radar images and through many years of experience, those responsible can tell whether it is a threatening thunderstorm front or a pure rain cell and in which direction the cells will probably go. Only when there is a serious danger to the fruit on the trees, the hail protection cannons are put into operation.
The accusation that the use of hail protection cannons prevents the clouds from raining down, is invalidated by Dr. Armin Raabe from the Institute of Meteorology of the University of Leipzig. He says -from his scientific perspective: “From this point of view, the generated sound field would be more likely to support rainwater production, regardless of whether or not there was an effect on hail suppression.” The spokeswoman emphasizes that rain is of immense importance for the agricultural company: “We manage more than 1,300 hectares of fruit acreage between Grimma, Döbeln and Oschatz. We only irrigate strawberries and a part of the pears. That’s less than 10 percent of the acreage. All other crops, such as apples, currants or plums, rely on naturally occurring precipitation and root-accessible water supplies in the soil.”
Modern corporate network
Together with the parent company there are eleven more subsidiaries that form Obstland Dürrweitzschen AG. The group of companies operates with around 380 employees in the fields of agriculture, trade and services. The group is known particularly for the production, processing and distribution of domestic fruits under the brand name “Sachsenobst”. This business division comprises six agricultural-oriented subsidiaries, Kelterei Sachsenobst GmbH and Sachsenobst Vermarktungsgesellschaft mbH.