why do my softdrinks cool as if in a refrigerator when buried underneath my campfire?

Question

Dug a hole and buried 6-pack in the beach sand. about 2 ft deep from surface.stacked driftwood on top and built fire for camp.after the fire had burned to coals.(about 3 hours or so)....removed coals and dug up cans of beverage.---felt and drank like had been in the frig.---i just had to try it.--friend told me about it.--i lost the bet.----ambient temperature was in the upper 90's

Answer 1

The cool temperature found at 2' depths is what cooled the soda. Sand is an excellent thermal insulator, so probably none of the heat from the fire reached even 1 foot deep, and the heat from the air also couldn't reach more than a couple inches. Did you notice that the sand felt cool that deep down? Next time take a little thermometer with you and bury it away from the fire, then read it when you did up the soda, I bet it says 'cool'.

Answer 2

The ground temperature in any given area is almost constant a few feet down. Usually not more that 60 deg F. Compared to 90 deg, that will be cool. The fire had nothing to do with it.

Answer 3

I'd have to agree with the person who mentioned the fact that sub-surface sand is often satuerated with water, combined with the fact that the sand insulated from the fire.