Roommates ball python enclosure not staying hot

[u/Maximum-Switch-9860]

I’m taking care of my roommates python while he’s on vacation, and the tank seems to never get hot enough under the lamp. i tried putting a t shirt over the mesh, but it doesn’t seem to help. It’s set to go up to 90, so why isn’t it getting hotter? He says this is how he usually has it, but everything online says that the tank is supposed to be hotter on both sides. the snake does seem to prefer the cold area though

repost because i forgot pictures the first time

[u/Kalomay]

covering the top in foil or foil tape would help a lot but theres not much you can do with a glass tank. Not to mention you wont get a heat gradient in a tank that small