On 21 June 2011, Nokia announced its first MeeGo/Harmattan smartphone device, Nokia N9. GKOS iPhone, Android phone/tablet and MeeGo Harmattan applications use this principle. The interface is clearly based on that of MeeGo Harmattan on the N9. Dry, dusty, harmattan winds occur from January to March. Harmattan winds cause the coldest weather between December and February. The interaction of the Harmattan with monsoon winds can cause tornadoes. The air is particularly dry and desiccating when the Harmattan blows over the region. In December and January, the city is affected by harmattan winds. The year begins under the influence of the harmattan winds in the dry season. This effect is known as the Harmattan haze. The dry season (December to April) is dominated by hot, dry, harmattan wind. This gives abandoned Harmattan or Symbian projects a new life. The harmattan is the prevailing wind. The Harmattan carries dust during the winter into the Gulf of Guinea. The dry season experiences two months of Harmattan from late December to late February.