Air Masses and Moisture

Istanbul's unique location leads to high amounts of precipitation. Its aquatic neighbors, the Black Sea and the Sea of Marmara, are huge providers or moisture and rain. However, it takes more than just nearby bodies of water to cause clouds and rain. The Atacama Desert is the driest place on earth and it directly on the coast of the Pacific Ocean. Along with a source of water you also need the movement of air and circulation. The image below shows the path of the solar eclipse of this past March, Turkey in red, but more importantly it clearly shows the air patterns common in this area. The Siberian Anticyclone is known to develop over Asia and circulates air past the Black Sea on its way to Turkey, bringing moist air onto land.

(Path of the March solar eclipse with Turkey in red - Source: http://eclipse.gsfc.nasa.gov)

Aiding in this movement are the several Mediterranean Lows. According to NASA there are a number of locations in the Mediterranean area that a common “sinks” of low-pressure systems. One of which just so happens to reside directly over Istanbul. This system usually develops in the string months but can be seen all year. It is this combination of the Siberian High, Mediterranean Lows, and the two seas that drives Istanbul’s weather and precipitation.

(Climate Classification for Turkey - Source: www.atc-anadolu.com)

The map above shows Istanbul classified as having a “humid” climate. Knowing its location and air patterns this seems perfectly reasonable.

(Precipitation for Turkey (mm) - Source: www.atc-anadolu.com)

Sources:

http://eclipse.gsfc.nasa.gov/SEpubs/20060329/text/section2.html

www.britannica.com/EBchecked/topic/372680/Mediterranean-low