every once and a while i drive up to the montains (my university is in a valley) just to cruise around alittle and there are some great roads up there.so there is this once turn about 3/4 of a mile long where you drop a few hundred feet in elevation. i was driving up there about 2 weeks ago and noticed when i speed down the montain at about 60-70 mph, when i get to the bottom the enginetemp needle goes down to about 1/4. today i tried it again and it did the same thing, it went down to about 1/4 then after driving a few mins, it returned to the mid point. my temp needle never moves from the mid. when im driving hard in the city on a hot day, stays in the middle. when im driving on the highway, stays in the middle, it never moves once the engine is warm.

so what do you think causes it to lower? im sure it has something to do with the pressure diffrence cause when i go down this turn i can feel my ears popping really badly.

 

It is probably just a pressure difference like you have stated but it could also be the gas moving around and throwing off the sensor.

 

yah man its nothing to worry about