2 crates of beer were packed in coolers and were brought on a camping trip. Each crate contains 12 bottles of beer that can fit into 1 cooler (2 coolers total). 

The night before the trip, a crate of beer bottles was refrigerated and the other crate was stocked at room temperature due to limited space in the fridge. 

In the morning, the bottles were packed in the cooler together with gel ice packs. Each cooler had 10 ice packs each and 12 beer bottles. Cooler 1 had the refrigerated beer while cooler 2 had the room temperature beer. 

Explain why the ice packs in cooler 1 were still solid while they were all melted in cooler 2 by the time the camping site was reached,