Sherry is made in the Jerez DO situated in the North East corner of Cadiz in Southern Spain. There are three main areas of the Jerez DO in which Sherry can be made: Jerez de la Frontera, the largest and also the capital city, El Puerto de Santa Maria and Sanlucar de Barrameda (where Manzanilla is produced). Jerez has a warm climate with very hot summers and mild winters characterised by two prevailing winds- the cool and humid Poniente from the west and the hot and dry Levante from the south-east- which markedly affect the different vineyard areas. The finest Sherries are made from grapes grown on the highly moisture-retaining white albariza soils and usually the white Palomino grape although Pedro Ximinez and Moscatel are also grown and used for blends and sweeter styles. Sherries are fortified after fermentation to either about 15% abv to allow the growth of the flor yeast which allows biological ageing to produce a Fino style of Sherry, or to about 18% abv to prevent the growth of flor allowing the wine to age oxidatively to produce an Oloroso style of Sherry. The fortified Sherry is then aged either biologically under flor or oxidatively for a minimum of 3 years in a dynamic system of cask stages that are continuously moved from cask stage to cask stage (running the scales) known as the Solera system. This continuous blending ensures continuity of character in the Solera system and also prevents vintage variation. Once bottled, sherry does not improve with age, however oxidatively aged sherries like Olorosos can last for a long time in bottle. There are many styles of Sherry which can be defined by where and how they are produced and also their alcohol and sugar content. They range from: Manzanilla, Fino, Amontillado, Oloroso, Palo Cortado, Pale Cream, Medium, Cream, Pedro Ximenenz and Moscatel.