Wrapping environmental objects/platforms

Hello again, I am currently having trouble with these clouds I want to move across the title screen. First off, I have this code in place. Sure the cloud moves but it just falls through the transparent boundary I've set and keeps going: #pragma strict

 var WhiteCloud : GameObject;
 var spawnPoint : Transform;
 
 function OnTriggerEnter(other : Collider){
     Destroy(other.gameObject);
     var WhiteCloud : GameObject = Instantiate(WhiteCloud,spawnPoint.position, Quaternion.identity);
     WhiteCloud.transform.position = spawnPoint.position;
 }

This may seem a bit insipid but I just edited a Player respawn code and replaced the player with the WhiteCloud that I am using. I even put the White Cloud and the transparent boundaries that are supposed to destroy it as prefabs. I'm really confused on what I'm supposed to do!