Severe winter weather has created treacherous conditions in several countries. A heavy snowfall in northern France stranded thousands of travelers in ParisÂ’ Charles de Gaulle airport Jan. 4 and tied up road traffic throughout the region. The snowfall was considered remarkable for Paris, where heavy snow is rare. Airports at Nimes and Montpellier were closed, and roads over the Pyrenees to Spain were also closed. Avalanche danger is high in the Alps and rivers have flooded in Belgium, Germany, Portugal and the U.K. A third of Venice was flooded Jan. 3, including St. MarkÂ’s Square. Trains in Sweden and Finland experienced heavy delays. GreeceÂ’s eastern Plaka region suffered mud slides and many roads were impassable. More than 400 homeless people have died in Poland and on the streets of Moscow because of the cold.