CAI- cold and warm air

I have a 91 Camaro 305 TBI V8 and made a cold air intake for my car. I put a temperature guage in the box because I was curious to see if it was working. (Im pretty vague so ask if questions).
The faster I go the higher the temp; obviousely no where near the engine temp, but warmer. The slower I go the colder the temp.
Can anyone explain this too me... thanks

where are you getting your cold air from?

From a tube that goes from the foglight hole to right under the snorkel, where it creates a cold air box of its own.