Why is it necessary for Turkish Coffee to start brewing with cold water?
Turkish coffee refers to the method of making coffee, not a type of coffee. Also known as mocha or kahve, it is traditionally made in an ibik using cold water to prolong the time the coffee "brews" and releases flavour. The ibik (aka cezve in Arabic) was invented in the 16th century, replacing the previous method of steeping the coffee in hot water set in sand on a tray over glowing embers for a whole day.



The Turkish coffee or mocha maker also aims to produce as much foam as possible and has to bring the mix of water. sugar and very finely ground mocha coffee slowly to the boil stirring all the time. Cold water ensures the maximum oxygen content in the water and therefore potentially more froth. As the coffee comes to the boil and the froth rises, it must be quickly removed from the heat before it boils over -- a little like boiled milk. 

Sometimes the froth is skimmed off and divided into the demitasse or mocha cups about three times before the coffee is finally served. The more proficient the mocha maker, the more foam they can produce. And a real Mocha Master knows exactly when to take the mocha off the hotplate at the first boil. Wait too long in the hope of obtaining more foam, and the coffee "catches" and is overcooked. It is then considered a failure and has to be thrown away, because it tastes too bitter and burnt. If, however, you get the timing right, the taste and the silkiness of the foam is unforgettable. Interesting to see that Wikipedia Turkish coffee page mistakenly shows a cezve and not an ibik serving Turkish coffee in Turkey.

In Turkey it is said when a girl can make coffee with a full "head" of froth, she is ready to marry. 

The Coffee Barer by John Frederick Lewis (1857) The Yorck Project: 10.000 Meisterwerke der Malerei. Licensed under Public domain via Wikimedia Commons