Description: The windis the result of sun action on Earth. The difference of temperature in the Earth makes air become hotter in some areas than in others. Hot air is lighter and less dense than cold air, and that is why it goes up. Earth areas where air rises are high pressure areas, whereas those where air goes down are low pressure areas. The difference in pressure is what gives wind its speed and direction. Apart from global scale winds generated by the difference of temperature between the equator and the rest of latitudes, there are many local winds caused by terrain orographic features, closeness to the sea, etc. One of the most important characteristics of the wind is its variability, both spatial and seasonal. There are variations in the average wind speed in the same location from one year to another, changes depending on the season, changes along the day, even variations from one second to another (turbulences). An atmospheric turbulence is characterized by a sudden change of wind direction and intensity. Turbulences also reduce the possibility of an efficient use of the wind in a wind turbine. They also produce more break downs and wear in wind turbines. When analysing the measurements taken by an anemometer in a given location, we can observe that it varies randomly but it keeps more steady in the rank between 10 minutes and 1 hour. So, calculating the average wind speed in that period will allow us to represent the wind behaviour along the day avoiding deviations produced by turbulences.
Professors: Default Professor, kurt demurie, Ivan Ivanov, Valérie Vanhecke, Momchil Merkulov, Rozalina Dimova, Dirk Bischof, Amaya Pierola Zabalza, Venci Valchev, Evaluator Evaluator, Angel Marinov, Orlin Stanchev, Emilian Bekov, Dirk Bischof, Fergal McEntee, Georgi Nikolov