The cloud is very big and puffy, and semi transparent. It is lime green and has a angry or bothered expression like most enemies. The cloud appears to have two eyes and a mouth; it looks like he is bloated up with methane or a type of gas. Its appearance is similar to that of the fart that the fart gun releases in the game Nitrome Must Die.
When the player first enters the level, the cloud is seen bobbing up and down. Hot Air Jr is looking confused, when all of a sudden it floats and goes in to Jr's head of his balloon.
The player's balloon is now pink and looks like it is holding its mouth in. The balloon will slowly expand, probably because the cloud contained some kind of gas. If the player doesn't reach the end of the level soon, the balloon will bloat up to a large size and will not be able to go through some spaces.
This forces the player to restart the level. This means the player has to go through obstacles and enemies at the fastest time possible, though they have to exercise caution as the balloon's bigger size can make it more prone to hit spikes. Along with the increase in size, which causes difficulty in getting places, when it is a certain size it will slowly pull the player up. This is problematic in the U shaped section at the end of the level, as lined on the ceiling and floor are spikes.