This statement is a fact. I know from personal experience. I observed when a gallon water jug was placed outside on a night reaching below freezing temperatures. The next morning after my dad went outside to grab the water jug, he found that there was a bulge on the side of the jug. This goes to show that when frozen, water expands, explaining as to why there was a bulge on the side of the gallon and all the water inside the jug had frozen and turned to ice.
So that the reader can get more absorbed in the passage .
