Warm spot and cool spot in cage

[akgrear]

I am new to this forum and my family is doing research on getting a veiled Chameleon. We have a Reptibreeze 16"x16"x30" vivarium. I have read that the cage needs to have a warm spot and a cool spot since the cage is tall and narrow and the heat light is at the top would the cool spot be on the bottom? I am not sure it's wide enough to have a cooler spot on one side and a warm spot on the other like I read. What do others do with a tall narrow cage?
I also know that we will have to upgrade when the chameleon gets too big but we are starting with this for now.

 

[Theveiled]

I think that's how it goes. Now that the question is brought up im not really sure of the correct answer. Starks bulb is at the middle of his cage and cooler near the bottom. He has diffeent branch levels to fit the temperature he wants

 

[Decadancin]

Warm at top and cooler below. Also a basking spot, so on spot warmer at the top. Actually, that makes both answers correct!