ABSTRACT
The major distinguishing feature of Central Eurasia’s climate is the dominance of dry climates and subsequently low amounts of rainfall. The dry climate regions, shown as BWk (mid-latitude desert) and BSk (mid-latitude steppe), are extensions of the vast areas of aridity that stretch across nearly one-third of Africa and into southwest Asia. Deserts are regions of little or no vegetation; steppes are grasslands or pasture areas suitable for raising wheat and some livestock, especially sheep and goats. Areas of perpetual aridity, such as the extensive areas that stretch from Turkmenistan into northwest China and Mongolia, are dominated by high pressure cells and belts for much of the year. The subtropical high pressure cell is the dominant pressure system during the summer; it basically prevents any regular rainfall from occurring. In addition the Himalayan mountain system effectively blocks rainfall that might come from monsoon South Asia. The windward side receives orographic rain; Central Asia is on the leeward side and receives little or none. Little moisture comes from the Mediterranean. In short, Central Asia has a continental climate (very hot in summer; very cold – the Siberian high – in winter) and is distant from any major moisture sources. Any low pressure cells in this mid-latitude westerly wind belt would have central European or Mediterranean sources and would lose moisture as they moved inland into continental Central Eurasia. The unpredictability of sustained rainfall regimes makes it difficult to raise crops that require significant amounts of moisture.
