Bordeaux wines are generally known by names of specific plots of land under single ownership. The Chateaux vary in size and this can increase and decrease with vineyard acquisition or sale so that the chateau name is more of a brand than a vineyard designation. Long hours of sunshine are moderated by a maritime climate and the major rivers provide humidity preventing frost. Being a temperate zone, vintages can vary considerably in quality although these differences can be reduced by strict grape and barrel selection. The best vineyards are found on well-draining, alluvial soils.