Be The Sea 
SEA ICE 
Ice whose origin is the sea is called sea ice. When the 
temperature of the sea reaches two or three degrees below 
freezing, the sea water itself begins to freeze. As sea water 
freezes, it separates from the dissolved salts and as a result 
Official U.S. Navy Photo 
Sludge ice in the Northern Pacific. 
sea ice may be fresh, although it often contains small amounts 
of occluded salt and bubbles of salt water within it. 
Let us examine the formation of sea ice. When the temper- 
ature of sea water falls to about —1.8° C., ice crystals form in 
the shape of thin plates an inch or so long. If they are suf- 
ficiently thick on the surface they form slush, the sea takes on 
