Name this Episode, Please!! ...from the original series

Why didn't I think of this before.... Surely Reddit will know!!

I have a very vague memory of a Star Trek episode I watched when I was little (thus I know it is from the ORIGINAL series). All I remember was this fascinating sequence where Kirk & Spock, I believe, were trapped in this environment which could change climates and topography within seconds. If I remember correctly, they ultimately discovered that they were in this big, white room. The climate changes may have been caused by an enemy trying to torment them. I remember a frigid snowstorm, among other things. THIS IS NOT THE HOLODECK FROM A LATER STAR TREK SERIES!!! as has been suggested to me many times. I KNOW this was an episode I saw in the 70's when I was little. It is possible that the holodeck was inspired by this episode...? All I remember was this blank slate of a gymnasium-sized room which could become any environment you (or the enemy) wanted it to be, and Kirk & Co. were trying to escape.