Snowfall on the Bosphorus Strait.
On Tuesday heavy snow forces Turkey to shut down the Strait.
The strait is one of the world's busiest waterways and is a vital artery for oil trade. Some 150 million tonnes of crude oil and petroleum products, mainly from Russia, transit the straits annually.
And it is not much better on land. On busy city streets citizens brace themselves against the cold.
(SOUNDBITE) (Turkish) ISTANBUL RESIDENT, SULEYMAN YILMAZ SAYING:
"It has completely affected daily life in Istanbul. No shops are open, and there is no traffic."
Snowfall in other areas is blanketing streets.
Cars are trapped in place.
Some are moving on despite the weather. Others are still digging out.
Deborah Lutterbeck, Reuters.