Re: cool sensation in-closed for sometime jar immediately after opening-why

The cool sensation that you feel when you put your hand in the jar is due 
to the moisture in the cookies that has gone into the air, on to your hand 
and evaporated again.
     Cookies have moisture in them (water) that keeps them tasty and soft. 
Eventually though, cookies dry out. They will dry out in a jar more slowly 
than out in the open, but they will still dry out until the moisture in 
the air matches the amount of moisture in the cookies. Where does the wet 
air go? On your hand! Now here's the tricky part. Your hand dries off 
within a few seconds, but while this is happening the water on your hand 
is taking some energy with it into the air, called evaporation. This makes 
your hand actually cool off just a little, but enough to feel the 
difference from the dry air.
     Really, the cool feeling is suppose to remind you that your mother is 
coming and you haven't asked for that cookie! Just kidding. :)