Adding dry ice in perishable shipments has been used as a cost effective solution to maintain cold temperatures for a limited time. Dry ice is solidified carbon dioxide (CO2) at very low temperature. Phase change diagrams establish the relationship between temperature, pressure and states of matter for carbon dioxide.

...Looking back, it was a tough week; one in which the harsh weather added a layer of unfriendliness.

And yet, knowing that at least 40 more people had somewhere to rest offered a sense of warmth and comfort even the hostile weather couldn’t dissipate.