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Some 3.5 billion people reside in urban areas. This number is projected to reach 6.3 billion by 2050, increasing from 50% to more than 70% of the world’s population. Cities are centres of creativity and economic progress but they also face many environmental challenges due mainly to air pollution and weather, climate and water-related hazard.
Sand and dust storms are common meteorological hazards in arid and semi-arid regions. They are usually caused by thunderstorms – or strong pressure gradients associated with cyclones – which increase wind speed over a wide area. These strong winds lift large amounts of sand and dust from bare, dry soils into the atmosphere, transporting them hundreds to thousands of kilometres away. Some 40% of aerosols in the troposphere (the lowest layer of Earth’s atmosphere) are dust particles from wind erosion.
Weather, climate and water impact on agriculture and fisheries, energy, transport, health, insurance, sports, tourism and many more socio-economic sectors. WMO promotes the application of meteorological, climatological, hydrological and oceanographic information in all human activities.